Heating electrode device, electrical heating glass, heat-generating plate, vehicle, window for building, sheet with conductor, conductive pattern sheet, conductive heat-generating body, laminated glass, and manufacturing method for conductive heat-generating body

ABSTRACT

A heating electrode device for energizing the heating a glass is provided. A heating electrode device includes a plurality of heat-generating conducting bodies extending as having a rectangular cross section and arranged in a direction different from the extending direction. In the cross section perpendicular to the extending direction of the heat-generating conducting body, when it is assumed that a thickness that is a size in a direction perpendicular to an arrangement direction be H and a size of a lager side of sides parallel to the arrangement direction be WB, H/WB&gt;1.0 is satisfied.

CROSS-REFERENCE TO RELATED APPLICATION

This is a Divisional of application Ser. No. 15/776,243 filed Jul. 6,2018, which in turn is a National Stage Application of PCT/JP2016/084086filed Nov. 17, 2016, which claims the benefit of Japanese PatentApplication No. 2015-224986 filed Nov. 17, 2015, Japanese PatentApplication No. 2015-237841 filed Dec. 4, 2015, Japanese PatentApplication No. 2015-238751 filed Dec. 7, 2015, Japanese PatentApplication No. 2015-245413 filed Dec. 16, 2015, Japanese PatentApplication No. 2015-245419 filed Dec. 16, 2015, Japanese PatentApplication No. 2015-248646 filed Dec. 21, 2015, and Japanese PatentApplication No. 2016-002857 filed Jan. 8, 2016. The disclosure of theprior applications are hereby incorporated by reference herein in itsentirety.

TECHNICAL FIELD

One aspect of the present invention relates to a heating electrodedevice including a heat-generating conducting body that is energized togenerate heat by Joule heat and an electrical heating glass using thesame.

Another aspect of the present invention relates to a heat-generatingplate having a heat-generating conductor, and a vehicle and a window fora building including such a heat-generating plate.

Still another aspect of the present invention relates to a sheet with aconductor having a heat-generating conductor, a heat-generating plate,and a vehicle and a window for a building including such aheat-generating plate.

Yet another aspect of the present invention relates to a conductiveheat-generating body, a laminated glass, and a manufacturing method fora conductive heat-generating body.

Still yet another aspect of the present invention relates to aheat-generating plate, a conductive pattern sheet, and a vehicle and awindow for a building including the heat-generating plate.

BACKGROUND ART

Conventionally, as disclosed in JP H08-72674 A, JP H09-207718 A, and JP2013-56811 A, there is a technique for heating a glass window for avehicle such as an automobile, a railway, an aircraft, and a ship and aglass window for a building by energization to eliminate freezing andfogging of the glass window. Such a glass window includes a heatingelectrode device between two glass plates. The heating electrode deviceincludes a pair of bus bar electrodes arranged separated from each otherand a plurality linear heat-generating conducting bodies arranged toconnect the pair of bus bar electrodes, and the heat-generatingconducting body can be energized by connecting the pair of bus barelectrodes to a power supply, and the heat-generating conducting body isheated so as to heat the glass window.

As a heater and a defroster, a heat-generating plate including theheat-generating conductor is used. For example, a vehicle using atransparent heat-generating plate for a front window (windshield) or arear window has been known, and by heating the heat-generatingconductor, excellent visibility can be secured by preventing frost, ice,and dew condensation on the vehicle window.

For example, JP 2013-173402 A discloses an anti-fog window for a vehiclein which an electric heater provided between transparent substratesheats the entire window. In addition, JP H08-72674 A discloses anelectric heating window glass that melts ice, frost, and prevents fog byheating a resistance heating line provided between two plate glasses.

Conventionally, a heat-generating plate which generates heat when avoltage is applied has been known. As a representative applicationexample, a transparent heat-generating plate is used as a defrosterdevice or a heater. The heat-generating plate as a defroster device isused for a window glass such as a front window (windshield) of a vehicleor a rear window. For example, in JP H08-72674 A and JP 2013-173402 A, aheat-generating plate having a visually transmitting performance is usedas a window glass. The heat-generating plate includes heat-generatingconductors formed of tungsten lines and the like arranged across theentire heat-generating plate. In the heat-generating plate, byenergizing the heat-generating conductor, the heat-generating conductoris heated by resistance heating. An increase in the temperature of awindow glass including the heat-generating plate removes fogging of thewindow glass or melts snow or ice attached on the window glass, and avisually transmitting performance through the window glass can besecured.

Conventionally, a window glass in which the conductive heat-generatingbody including a heating wire is incorporated has been known as adefroster device used for a window glass such as a front window or arear window of a vehicle. In such a defroster device, the conductiveheat-generating body incorporated in the window glass is energized toincrease the temperature of the window glass by resistance heating, andfogging of the window glass is removed, and snow or ice attached on thewindow glass is melted, and passenger's visibility can be secured.

As a material of the conductive heat-generating body, various materialshave been conventionally used. However, there is a problem in that lightbeams diffracted by the conductive heat-generating body interfere witheach other and cause a beam of light if the conductive heat-generatingbodies are regularly arranged in the window glass. A beam of light is aphenomenon in which streaky light is visually recognized.

Furthermore, if the conductive heat-generating body is linearlyextended, external light entering the conductive heat-generating body isreflected in the substantially same direction, and human eyes positionedin this direction feel strong flicker (glare).

JP 2011-210487 A discloses that the conductive heat-generating body isformed as a wavy path and each of a plurality of wavy lines forming eachwavy path is irregularly formed for each half period to prevent flicker.

Conventionally, as a defroster device used for a window glass such as afront window or a rear window of a vehicle, a window glass havingheating wires formed of tungsten lines and the like are arranged in theentire window glass has been known. In the related art, the heatingwires arranged in the entire window glass are energized to increase thetemperature of the window glass by resistance heating, and fogging onthe window glass is removed or snow or ice attached on the window glassis melted, and the passenger's visibility can be secured.

Recently, a defroster device in which a conductive pattern is producedby using photolithography technique instead of the heating wires formedof tungsten lines and the like and the conductive pattern is energizedto increase the temperature of the window glass by resistance heatinghas been known (refer to JP 2011-216378 A and JP 2012-151116 A). Thismethod has an advantage such that a conductive pattern with acomplicated shape can be easily formed. In JP 2011-216378 A and JP2012-151116 A, for example, a conductive pattern having an irregularshape obtained from the Voronoi diagram generated from sitesspecifically and randomly distributed in a planer surface is formed andused as a heating wire for increasing the temperature of the windowglass.

SUMMARY OF INVENTION Technical Problem

As disclosed in JP H08-72674 A, JP H09-207718 A, and JP 2013-56811 A,the conventional heat-generating conducting body has been often formedby using a tungsten wire having a circular cross section.

Here, since the tungsten wire has a circular cross section, it isnecessary to increase a wire diameter when increasing a cross sectionalarea to improve a heat generation performance (high output). In a caseof the circular cross section, the cross sectional area is not maximized(conversely, minimized) relative to the diameter (corresponding to crosssectional area for interfering field of view).

As described above, conventionally, there has been a problem in that itis necessary to increase the diameter of the circular cross section toincrease the cross sectional area of the heat-generating conducting bodyand the heat-generating conducting body is visually recognized due to anincrease in the width of the heat-generating conducting body. As aresult, it is difficult to achieve both of invisibility of theheat-generating conducting body and improvement of a heat generationperformance.

Accordingly, a first object of the present invention is to provide aheating electrode device that efficiently increases a cross sectionalarea while preventing an increase in a width of a heat-generatingconducting body and is hardly visually recognized even with a highoutput. Furthermore, an electrical heating glass having the heatingelectrode device is provided.

As disclosed in JP H08-72674 A, JP H09-207718 A, and JP 2013-56811 A,the heat-generating conducting body has been conventionally formed in awavy form. This is to prevent a beam of light caused by a pattern of theheat-generating conducting bodies periodically arranged at predeterminedintervals.

However, the heat-generating conducting body is formed in a wavy form, aheating value is reduced in comparison with a case where theheat-generating conducting body is linearly formed, and removal frostand fogging takes longer time.

Accordingly, a second object of the present invention is to provide aheating electrode device that can reduce a time to remove frost andfogging while preventing a beam of light. Furthermore, an electricalheating glass having the heating electrode device is provided.

In the heat-generating plate suitable for a heater and a defroster, thinlinear heat-generating conductors (referred to as “conductive thin wire”below) are regularly arranged between plates. For example, in ananti-fog window for a vehicle disclosed in JP 2013-173402 A, a pluralityof wavy conductive wires is printed and formed in the same arrangementpattern. In addition, in an electric heating window glass disclosed inJP H08-72674 A, a plurality of resistance heating lines having asinusoidal shape is arranged in parallel.

When light emitted from a light source such as illumination (inparticular, point light source) is viewed through a transparentheat-generating plate including a large number of conductive thin wires,a so-called “beam of light” occurs that is emitted, around the lightsource, to be observed as light extending in an elongated radial shapefrom the light source toward the surroundings. The beam of light affectsthe visibility. For example, when a beam of light occurs in lightobserved by a driver through a vehicle window, the beam of light mayinterfere the driver's visibility. Therefore, from the viewpoint ofsecuring excellent visibility, it is preferable to prevent theoccurrence of the beam of light as possible.

As a result of intensive research, the inventors of the presentinvention have found that a beam of light can occur due to diffractionof light by the heat-generating conductor (conductive thin wire) andnewly found that occurrence of a beam of light can be effectivelyavoided by preventing visual recognition of diffraction light caused bythe heat-generating conductor.

Furthermore, as a result of further research, the inventors of thepresent invention have acquired knowledges such that it is difficult tosecure excellent visibility while preventing occurrence of a beam oflight and preventing glare that may impair the field of view.Particularly, in a case where the heat-generating plate is used for awindow, since the heat-generating conductor naturally exists in thefield of view, it is very difficult to achieve both to secure clearvisibility and to prevent dazzle and blur that may cause eyestrain at ahigh level.

The present invention has been made in consideration of abovecircumstances, and a third object of the present invention is to providea heat-generating plate that can secure excellent visibility whilepreventing occurrence of a beam of light and a vehicle and a window fora building including the heat-generating plate.

In the conventional heat-generating plate, the conductive thin wire ofthe heat-generating conductor linearly extends to couple the pair of busbars. In such a heat-generating plate, a portion where heat cannot begenerated due to disconnection of the heat-generating conductor is made,and uneven heat generation is caused. As a result of intensive researchby the inventors of the present invention, it has found that ease todisconnect the conductive thin wire of the heat-generating conductordepends on the width of the conductive thin wire. When the conductivethin wire is arranged in a curved shape, particularly in a portion wherea curvature is large, a portion with a narrow line width is easilydisconnected by etching in a manufacturing process.

It is considered to thicken the line width of the conductive thin wireto prevent the disconnection. However, when the line width is thicker,the conductive thin wire is visually recognized in an appearance of theheat-generating plate, and visibility and design are deteriorated.Therefore, it is necessary to form the conductive thin wire with theline width with which disconnection hardly occurs and the conductivethin wire is not visually recognized. The present invention has beenmade in consideration of above points, and a fourth object of thepresent invention is to provide a heat-generating plate with whichdisconnection of the conductive thin wire of the heat-generatingconductor hardly occurs and the conductive thin wire is not visuallyrecognized.

In the conventional heat-generating plate, the conductive thin wire ofthe heat-generating conductor linearly extends to couple the pair of busbars. In such a heat-generating plate, a portion where heat cannot begenerated due to disconnection of the heat-generating conductor is made,and uneven heat generation is caused. Therefore, it has been consideredto connect between linearly extending conductive thin wires so as tomaintain electric connection even when disconnection occurs. As theeasiest method, to connect between the linearly extending conductivethin wires with a linear bridge is considered. However, in this case, anorientation direction of the bridge is conspicuous when an entireheat-generating plate is observed, and streaky light referred to as abeam of light occurs. Therefore, visibility through the heat-generatingplate is deteriorated.

The present invention has been made in consideration of above points,and a fifth object is to provide a heat-generating plate that does noteasily cause uneven heat generation even when the heat-generatingconductor is disconnected and does not deteriorate visibility.

Furthermore, with a conductive film having a wavy path disclosed in JP2011-210487 A, glare may be certainly reduced. However, since the shapesof the wavy paths are irregularly formed, there are a portion with ahigh temperature and a portion with a low temperature, and uneven heatmay be caused. Therefore, for example, when the conductive filmdisclosed in JP 2011-210487 A is incorporated in a window glass of avehicle, a place where fogging is removed and a place where fogging isnot removed, or a place where snow or ice is melted or a place wheresnow or ice is not melted are made in the window glass, and there is apossibility that passenger's visibility cannot be satisfactorilysecured.

The present invention has been made to solve the above problems, and asixth object of the present invention is to provide a conductiveheat-generating body and a laminated glass capable of preventing unevenheat while preventing a beam of light and flicker and a manufacturingmethod therefor.

FIG. 92 illustrates a partially enlarged conductive pattern 840 in aconventional defroster device disclosed in JP 2011-216378 A and JP2012-151116 A. In the conventional defroster device, the conductivepattern 840 includes a plurality of connection elements 844 extendingbetween two branch points 842 and defining an opening region 843, andeach connection element 844 is formed of a single straight line segment.As a result of intensive research on the defroster device including sucha connection element 844 by the inventors of the present invention, ithas been found that an observer (for example, passenger such as driver)can visually recognize the conductive pattern 840 including theconnection elements 844 depending on the shape of each connectionelement 844 formed of a single straight line segment. When light such asexternal light entering the defroster device enters a side surfaceformed by a flat surface of the connection element 844, the light thathas entered each position on the side surface is reflected by the sidesurface in a substantially constant direction. Then, the reflected lightis visually recognized by the observer so that the conductive pattern840 including the connection elements 844 is visually recognized by theobserver. The visual recognition of the conductive pattern 840 includingthe connection elements 844 by the observer such as a driverdeteriorates visibility of the observer through the window glass.

The present invention has been made in consideration of these points,and a seventh object of the present invention is to improve invisibilityof a conductive pattern of a defroster device.

Solution to Problem

The present invention will be described below. Here, for easyunderstanding, reference numerals in the drawings are attached. However,the present invention is not limited to this.

[First Invention]

One aspect of the present invention is a heating electrode device, forenergizing and heating glass, that includes a plurality ofheat-generating conducting bodies configured to extend as having arectangular cross section and arranged in a direction different from theextending direction, in which regarding the heat-generating conductingbody, when it is assumed that a thickness which is a size in a directionperpendicular to an arrangement direction of a cross sectionperpendicular to the extending direction be H and a size of a largerside of sides parallel to the arrangement direction be W_(B),H/W_(B)>1.0 is satisfied, and the problems are solved by the heatingelectrode device.

Another aspect of the present invention is the heating electrode devicein which, in the cross section of the heat-generating conducting bodyperpendicular to the extending direction, when it is assumed that a sizeof an opposite side from the side having the size of W_(B) be W_(T),W_(B)>W_(T), 3 μm≤W_(B)≤15 μm, and 1 μm≤W_(T)≤12 μm are satisfied.

Still another aspect of the present invention is any one of the heatingelectrode devices that includes a transparent base material layer and inwhich the heat-generating conducting body is arranged on one surface ofthe base material layer, and one surface of the heat-generatingconducting body has contact with the surface of the base material layer.

Still another aspect of the present invention is an electrical heatingglass including a transparent first panel, a transparent second panelarranged as having a gap with the first panel, and any one of theheating electrode devices arranged in the gap between the first paneland the second panel.

According to each aspect of the present invention, in the heatingelectrode device and the electrical heating glass using the same, thecross sectional area is efficiently increased while preventing anincrease in a width of the heat-generating conducting body, and theheat-generating conducting body can be hardly visually recognized whileobtaining a high output. The function can be enhanced.

[Second Invention]

Another aspect of the present invention is a heating electrode devicefor energizing and heating glass that includes a plurality of linearheat-generating conducting bodies and in which, regarding theheat-generating conducting body, when it is assumed that a distancebetween both ends be D (mm) and a length along the heat-generatingconducting body between both ends be L (mm), 1.02·D≤L<1.50·D issatisfied, and the heating electrode device solves the above problems.

Still another aspect of the present invention is the heating electrodedevice in which when it is assumed that a pitch of the plurality ofheat-generating conducting bodies be P (mm), a surface area of onesurface of the heat-generating conducting body in a thickness directionper length of 0.01 m in a plan view be S_(B) (μm²), and a surface areaof the other surface per length of 0.01 m in a plan view be S_(T) (μm²),0.5 mm≤P≤5.00 mm and 0 μm²<S_(B)−S_(T)≤30000 μm² are satisfied.

Yet another aspect of the present invention is the heating electrodedevice in which, in the cross section perpendicular to the extendingdirection of the heat-generating conducting body, when it is assumedthat a length of a side on the side of S_(B) (μm²) be W_(B) (μm), and alength of a side on the side of S_(T) (μm²) be W_(T) (μm), W_(B)>W_(T),3 μm≤W_(B)≤15 μm, and 1 μm≤W_(T)≤12 μm are satisfied.

Still yet another aspect of the present invention is any one of theheating electrode devices that includes a transparent base materiallayer and in which the heat-generating conducting body is arranged onone surface of the base material layer, and one surface of theheat-generating conducting body has contact with the surface of the basematerial layer.

Still another aspect of the present invention is an electrical heatingglass including a transparent first panel, a transparent second panelarranged as having a gap with the first panel, and any one of theheating electrode devices arranged in the gap between the first paneland the second panel.

According to each aspect of the present invention, in the heatingelectrode device and the electrical heating glass using the same, aheating value can be satisfactorily secured while preventing a beam oflight, and fogging and frost can be smoothly eliminated.

[Third Invention]

Another aspect of the present invention relates to a heat-generatingplate that includes a supporting base material, a pair of bus bars towhich a voltage is applied, and a heat-generating conductor supported bythe supporting base material and connected to the pair of bus bars, inwhich the heat-generating conductor includes a conductive main thin wirethat extends between the pair of bus bars and includes a first largecurvature portion having a relatively large curvature and a first smallcurvature portion having a relatively small curvature, and aninclination of a cross sectional area of the first large curvatureportion of the conductive main thin wire is larger than an inclinationof the cross sectional area of the first small curvature portion.

According to the present aspect, even when the heat-generating conductorincludes the conductive main thin wire, both of prevention of occurrenceof a beam of light and antiglare can be achieved at a high level.

It is preferable that the cross sectional area of the conductive mainthin wire be divided by a lower bottom having contact with thesupporting base material, an upper bottom arranged at a position facingto the lower bottom, a first inclined portion extending between an endof the lower bottom and an end of the upper bottom, and a secondinclined portion extending between the other end of the lower bottom andthe other end of the upper bottom, and an inclination of the crosssectional area be expressed by each of an inclination of a straight linepassing through the end of the lower bottom and the end of the upperbottom, and an inclination of a straight line passing through the otherend of the lower bottom and the other end of the upper bottom.

According to the present aspect, the inclination of the cross sectionalarea of the conductive main thin wire is appropriately expressed.

A sum of projection sizes of the first inclined portion and the secondinclined portion of the cross sectional area of the first smallcurvature portion on the supporting base material may be larger than asum of projection sizes of the first inclined portion and the secondinclined portion of the cross sectional area of the first largecurvature portion on the supporting base material.

According to the present aspect, the sizes of the first inclined portionand the second inclined portion in the conductive main thin wire whicheasily contribute to generate glare by light reflection can be changedbetween the first large curvature portion and the first small curvatureportion, and it is possible to prevent the glare from being emphasizedby light reflection.

Projection of the cross sectional area of the first small curvatureportion on the supporting base material may be larger than projection ofthe cross sectional area of the first large curvature portion on thesupporting base material.

According to the present aspect, the size of the portion in theconductive main thin wire that can contribute to the reflection of lightcan be changed between the first large curvature portion and the firstsmall curvature portion, and it is possible to prevent the glare such asdazzle and blur from being emphasized by light reflection.

A gap between the upper bottom and the lower bottom of the crosssectional area of the first small curvature portion may be equal to agap between the upper bottom and the lower bottom of the cross sectionalarea of the first large curvature portion.

According to the present aspect, good workability of the heat-generatingconductor is secured, and the first large curvature portion and thefirst small curvature portion can be easily formed.

The plurality of conductive main thin wires is provided, and theheat-generating conductor may further include a conductive sub thin wirefor coupling the conductive main thin wires arranged adjacent to eachother in at least a part of the plurality of conductive main thin wires.

According to the present aspect, since the conductive main thin wiresare connected to each other with the conductive sub thin wire, even whena part of the conductive main thin wire is disconnected, electric powercan be supplied from the other conductive main thin wire to thedisconnected conductive main thin wire via the conductive sub thin wire.Therefore, uneven heat generation can be effectively reduced.

The conductive sub thin wire may include a second large curvatureportion having a relatively large curvature and a second small curvatureportion having a relatively small curvature.

According to the present aspect, the conductive sub thin wire isarranged in a curved shape, and a visible beam of light which can beeffectively prevented.

The heat-generating plate may further include a covering member forcovering the heat-generating conductor, and the heat-generatingconductor may be arranged between the supporting base material and thecovering member.

According to the present aspect, it is possible to provide theheat-generating plate in which the heat-generating conductor is arrangedbetween the supporting base material and the covering member, and theheat-generating plate can be easily applied to various windows.

Another aspect of the present invention relates to a vehicle includingthe heat-generating plate.

Another aspect of the present invention relates to a window for abuilding including the heat-generating plate.

According to each aspect of the present invention, since the inclinationof the cross sectional area of the “first large curvature portion havinga relatively large curvature” of the cross sectional area of theconductive main thin wire of the heat-generating conductor is largerthan the inclination of the cross sectional area of the “first smallcurvature portion having a relatively small curvature”, both ofprevention of occurrence of a beam of light and antiglare can beachieved at a high level.

[Fourth Invention]

A heat-generating plate according to another aspect of the presentinvention, which generates heat when a voltage is applied, includes apair of glasses, a pair of bus bars to which a voltage is applied, and aheat-generating conductor that couples between the pair of bus bars, inwhich the heat-generating conductor includes a plurality of conductivethin wires that linearly extends between the pair of bus bars andcouples between the pair of bus bars, and an average W_(ave) of a widthW of of the conductive thin wire is within a rangeofthe followingformula (a) relative to a standard deviation a of distribution of thewidth W.

0≤4σ/W _(ave)≤0.3  Formula (a)

In the heat-generating plate according to another aspect of the presentinvention, the conductive thin wire includes a large curvature portionhaving a relatively large curvature and a small curvature portion havinga relatively small curvature, and the width W of the conductive thinwire may be thin in the large curvature portion and may be thick in thesmall curvature portion.

A vehicle according to another aspect of the present invention includesany one of the heat-generating plates according to the presentinvention.

A window for a building according to another aspect of the presentinvention includes any one of the heat-generating plates according tothe present invention.

According to each aspect of the present invention, the conductive thinwire of the heat-generating conductor of the heat-generating plate canbe hardly disconnected.

[Fifth Invention]

A heat-generating plate according to another aspect of the presentinvention is a heat-generating plate, which generates heat when avoltage is applied, includes a pair of glasses, a pair of bus bars towhich a voltage is applied, and a heat-generating conductor that couplesbetween the pair of bus bars, in which the heat-generating conductorincludes a plurality of conductive thin wires that linearly extendsbetween the pair of bus bars and couples between the pair of bus barsand a coupling conductive thin wire for coupling between two adjacentmain conductive thin wires, and each coupling conductive thin wire hasthree or more different patterns.

In the heat-generating plate according to another aspect of the presentinvention, the pattern of the coupling conductive thin wire may be astraight line, a circular arc, or a combination of a straight line and acircular arc.

In the heat-generating plate according to another aspect of the presentinvention, each coupling conductive thin wire may have a patterndifferent from those of all the other coupling conductive thin wires.

A vehicle according to another aspect of the present invention includesany one of the heat-generating plates according to the presentinvention.

A window for a building according to another aspect of the presentinvention includes any one of the heat-generating plates according tothe present invention.

A sheet with a conductor according to another aspect of the presentinvention is a sheet with a conductor, which is used for aheat-generating plate that generates heat when a voltage is applied,includes a base film, a pair of bus bars to which a voltage is applied,and a heat-generating conductor that couples between the pair of busbars, in which the heat-generating conductor includes a plurality ofconductive thin wires that linearly extends between the pair of bus barsand couples between the pair of bus bars and a coupling conductive thinwire for coupling between two adjacent main conductive thin wires, andeach coupling conductive thin wire has three or more different patterns.

According to each aspect of the present invention, even when theheat-generating conductor of the heat-generating plate is disconnected,uneven heat generation hardly occurs, and it is possible to preventdeterioration in visibility.

[Sixth Invention]

To solve the above problems, in another aspect of the present invention,a conductive heat-generating body is provided which includes a pluralityof curved heat-generating bodies arranged separated from each other in afirst direction and extending in a second direction intersecting withthe first direction, in which a ratio of an entire length of each of theplurality of curved heat-generating bodies in the second directiondivided by a shortest distance between both ends of each of theplurality of curved heat-generating bodies is larger than 1.0 and equalto or less than 1.5.

Each of the plurality of curved heat-generating bodies may be formed byconnecting a plurality of periodic curved lines having irregular periodsand amplitudes for each period along the second direction.

End positions of ends of the plurality of curved heat-generating bodiesin the second direction may be irregular.

A bypass heat-generating body that connects the two adjacent curvedheat-generating bodies in the first direction may be included.

Connection positions of the bypass heat-generating body may be irregularfor each of the plurality of curved heat-generating bodies.

A plurality of heat-generating body rows of which some ofheat-generating body rows are aligned in each of the first direction andthe second direction may be included, each of the plurality ofheat-generating body rows may include the plurality of curvedheat-generating bodies, and the corresponding curved heat-generatingbodies in two heat-generating body rows arranged adjacent to each otherin the second direction may be connected to each other.

A shortest distance between both ends of each of the plurality of curvedheat-generating bodies included in each of the plurality ofheat-generating body rows may be equal to or more than 50 mm.

A pair of bus bar electrodes arranged separated from each other in thesecond direction and extending in the first direction and a plurality ofwavy line heat-generating bodies arranged separated from each other inthe first direction and extending in the second direction to beconnected to the pair of bus bar electrodes may be included, and theplurality of wavy line heat-generating bodies may be formed byconnecting the plurality of curved heat-generating bodies included ineach of the plurality of heat-generating body rows in the seconddirection.

A transparent base material layer in which the plurality of curvedheat-generating bodies is arranged on one principal surface may beincluded.

A laminated glass may be used which includes a pair of glass substratesarranged to face to each other so as to sandwich the conductiveheat-generating body.

In another aspect of the present invention, a manufacturing method for aconductive heat-generating body is provided that includes a step forgenerating a single curved heat-generating body by connecting aplurality of periodic curved lines having periods and amplitudes thatare irregular for each period along a second direction intersecting witha first direction, a step for performing normalization processing foradjusting the periods of the plurality of periodic curved lines includedin the curved heat-generating body so that a shortest distance is afirst limited value in a case where the shortest distance between bothends of the curved heat-generating body exceeds the first limited value,a step for generating the single curved heat-generating body again whenit is determined whether a ratio obtained by dividing an entire lengthof the normalized curved heat-generating body in the second direction bythe first limited value is within a range larger than 1.0 and equal toor less than 1.5 and it is determined that the ratio is not within therange, a step for generating the plurality of curved heat-generatingbodies arranged separated from each other in the first direction byrepeating generation of the single curved heat-generating body and thenormalization processing in a position with a predetermined intervalfrom the normalized curved heat-generating body when it is determinedthat the ratio is within the range, a step for adjusting a phase to makethe phases of the plurality of curved heat-generating bodies in thesecond direction be irregular and generating a heat-generating body rowincluding the plurality of curved heat-generating bodies of which aphase has been adjusted, and a step for forming a pair of bus barelectrodes arranged separated from each other in the second direction ona transparent base material and extending along the first direction andarranging the plurality of heat-generating body rows in the firstdirection and the second direction between the pair of bus barelectrodes to form a plurality of wavy line conductors connected to thepair of bus bar electrodes and arranged separated from each other in thefirst direction.

According to each aspect of the present invention, uneven heat can beprevented while preventing a beam of light and flicker.

[Seventh Invention]

A heat-generating plate according to another aspect of the presentinvention includes a pair of glass plates, a conductive pattern arrangedbetween the pair of glass plates and defining a plurality of openingregions, and a bonding layer arranged between the conductive pattern andat least one of the pair of glass plates, in which the conductivepattern includes a plurality of connection elements for extendingbetween two branch points and defining the opening region, and theconnection elements for connecting the two branch points as a straightline segment are less than 20% of the plurality of connection elements.

In the heat-generating plate according to the aspect of the presentinvention, an average distance between median points of the two adjacentopening regions may be equal to or more than 50 μm.

In the heat-generating plate according to the aspect of the presentinvention, the thickness of the conductive pattern may be equal to ormore than 2 μm.

In the heat-generating plate according to the aspect of the presentinvention, an average of a ratio (L₁/L₂) of a length L₁ of each openingregion along the first direction relative to a length L₂ of the openingregion along the second direction perpendicular to the first directionmay be equal to or more than 1.3 and equal to or less than 1.8.

A conductive pattern sheet according to another aspect of the presentinvention includes a base material and a conductive pattern provided onthe base material and defining a plurality of opening regions, in whichthe conductive pattern includes a plurality of connection elementsextending between two branch points and defining the opening region, andthe connection elements for connecting the two branch points as astraight line segment are less than 20% of the plurality of connectionelements.

A vehicle according to another aspect of the present invention includesthe heat-generating plate described above.

A window for a building according to another aspect of the presentinvention includes the heat-generating plate described above.

According to each aspect of the present invention, invisibility of theconductive pattern of the defroster device can be improved.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1(a) is a plan view for explaining an electrical heating glassaccording to one embodiment, FIG. 1(b) is an enlarged view of aheat-generating conducting body which is one example of aheat-generating conducting body, and FIG. 1(c) is an enlarged view of aheat-generating conducting body which is another example of theheat-generating conducting body.

FIG. 2 is a cross-sectional view for explaining a layer structure of theelectrical heating glass.

FIG. 3 is a perspective view for explaining a heating electrode device.

FIG. 4 is a view for explaining a form of the heat-generating conductingbody.

FIGS. 5(a) to 5(d) are diagrams for explaining a method for producingthe electrical heating glass.

FIG. 6(a) is a plan view for explaining an electrical heating glassaccording to one embodiment, and FIG. 6(b) is an enlarged view of aheat-generating conducting body which is one example of aheat-generating conducting body.

FIG. 7 is a cross-sectional view for explaining a layer structure of theelectrical heating glass.

FIG. 8 is a perspective view for explaining the heating electrodedevice.

FIG. 9 is a view for explaining a form of the heat-generating conductingbody.

FIGS. 10(a) to 10(d) are diagrams for explaining a method for producingthe electrical heating glass.

FIG. 11A is a diagram for explaining a relationship between a crosssectional shape of a thin linear heat-generating conductor and a lightreflection aspect and indicates an example of the heat-generatingconductor having a rectangular cross section.

FIG. 11B is a diagram for explaining a relationship between a crosssectional shape of a thin linear heat-generating conductor and a lightreflection aspect and indicates an example of the heat-generatingconductor having a non-rectangular cross section.

FIG. 12 is a perspective view for schematically illustrating anautomobile (vehicle) on which a battery (power supply) is mounted.

FIG. 13 is a front view of a front window including a transparentheat-generating plate.

FIG. 14 is a cross-sectional view of the heat-generating plate (frontwindow) taking along a line XIV-XIV illustrated in FIG. 13.

FIG. 15 is an enlarged plan view illustrating an exemplary wiringpattern of the heat-generating conductor.

FIG. 16A is an enlarged view of a portion (first small curvatureportion) indicated by a reference numeral “31 a” in FIG. 15.

FIG. 16B is an enlarged view of a portion (first large curvatureportion) indicated by a reference numeral “31 b” in FIG. 15.

FIG. 17A is a cross-sectional view taken along a line XVIIA-XVIIA inFIG. 16A.

FIG. 17B is a cross-sectional view along a line XVIIB-XVIIB in FIG. 16B.

FIG. 18 is a cross-sectional view illustrating a modification of theheat-generating plate.

FIG. 19 is a cross-sectional view illustrating one process of amanufacturing method for the heat-generating plate.

FIG. 20 is a cross-sectional view illustrating one process of themanufacturing method for the heat-generating plate.

FIG. 21 is a cross-sectional view illustrating one process of themanufacturing method for the heat-generating plate.

FIG. 22 is a cross-sectional view illustrating one process of themanufacturing method for the heat-generating plate.

FIG. 23 is a cross-sectional view illustrating one process of themanufacturing method for the heat-generating plate.

FIG. 24 is a cross-sectional view illustrating one process of themanufacturing method for the heat-generating plate.

FIG. 25 is a cross-sectional view illustrating one process of themanufacturing method for the heat-generating plate.

FIG. 26 is a cross-sectional view illustrating another modification ofthe heat-generating plate.

FIG. 27 is a cross-sectional view illustrating still anothermodification of the heat-generating plate.

FIG. 28 is a cross-sectional view illustrating yet another modificationof the heat-generating plate.

FIG. 29 is a view for explaining an embodiment according to the presentinvention and is a perspective view schematically illustrating a vehicleincluding a heat-generating plate. Particularly, in FIG. 29, anautomobile including a front window configured by the heat-generatingplate is schematically illustrated as an example of the vehicle.

FIG. 30 is a view illustrating the heat-generating plate from a normaldirection of a plate surface.

FIG. 31 is a cross-sectional view of the heat-generating plate takenalong a line XXXI-XXXI in FIG. 30.

FIG. 32 is a plan view illustrating a sheet with a conductor from anormal direction of a sheet surface and is a plan view of an example ofthe sheet with a conductor.

FIG. 33 is a plan view in which a part of a conductive thin wire isenlarged and illustrated.

FIG. 34 is an enlarged cross-sectional view of the sheet with aconductor.

FIG. 35 is a view for explaining an example of a manufacturing methodfor a heat-generating plate.

FIG. 36 is a view for explaining an example of the manufacturing methodfor the heat-generating plate.

FIG. 37 is a view for explaining an example of the manufacturing methodfor the heat-generating plate.

FIG. 38 is a view for explaining an example of the manufacturing methodfor the heat-generating plate.

FIG. 39 is a view for explaining an example of the manufacturing methodfor the heat-generating plate.

FIG. 40 is a view for explaining an example of the manufacturing methodfor the heat-generating plate.

FIG. 41 is a view for explaining an example of the manufacturing methodfor the heat-generating plate.

FIG. 42 is a view for explaining an example of the manufacturing methodfor the heat-generating plate.

FIG. 43 is a view for explaining an example of the manufacturing methodfor the heat-generating plate.

FIG. 44 is a view for explaining an embodiment according to the presentinvention and is a perspective view schematically illustrating a vehicleincluding a heat-generating plate. Particularly, in FIG. 44, anautomobile including a front window configured by the heat-generatingplate is schematically illustrated as an example of the vehicle.

FIG. 45 is a view illustrating the heat-generating plate from a normaldirection of a plate surface.

FIG. 46 is a cross-sectional view of the heat-generating plate takenalong a line XLVI-XLVI in FIG. 44.

FIG. 47 is a plan view illustrating a sheet with a conductor from anormal direction of a sheet surface and is a plan view of an example ofthe sheet with a conductor.

FIG. 48 is a view for explaining an example of a manufacturing methodfor the heat-generating plate.

FIG. 49 is a view for explaining an example of the manufacturing methodfor the heat-generating plate.

FIG. 50 is a view for explaining an example of the manufacturing methodfor the heat-generating plate.

FIG. 51 is a view for explaining an example of the manufacturing methodfor the heat-generating plate.

FIG. 52 is a view for explaining an example of the manufacturing methodfor the heat-generating plate.

FIG. 53 is a view for explaining an example of the manufacturing methodfor the heat-generating plate.

FIG. 54 is a view for explaining an example of the manufacturing methodfor the heat-generating plate.

FIG. 55 is a plan view of a conductive heat-generating body according toan embodiment of the present invention.

FIG. 56 is a diagram of a plurality of heat-generating body rowsarranged along a vertical direction and a horizontal direction.

FIG. 57 is a block diagram illustrating a schematic configuration of aheat-generating body generating device that automatically generates aplurality of curved heat-generating bodies included in theheat-generating body row.

FIG. 58 is a flowchart illustrating an example of a processing procedureof the heat-generating body generating device in FIG. 57.

FIG. 59 is a plan view of a conductive heat-generating body havingbypass heat-generating bodies.

FIG. 60 is a view illustrating an example in which a conductiveheat-generating body is incorporated in a front window of a car.

FIG. 61 is a diagram in which two bus bar electrodes are arranged alongsides on both ends of the front window in a short-side direction and aplurality of wavy line conductors is arranged along a longitudinaldirection of the front window.

FIG. 62 is a perspective view of a vehicle.

FIG. 63 is a cross-sectional view taken along a line LXIII-LXIII in FIG.60 of the front window.

FIGS. 64(a) to 64(e) are cross-sectional views illustrating a processfor manufacturing a conductive heat-generating body.

FIG. 65 is a cross-sectional view of a heating element sheet.

FIG. 66 is a cross-sectional view illustrating an example of a processfor manufacturing a laminated glass using the heating element sheet inFIG. 65.

FIG. 67 is a cross-sectional view of the manufacturing processsubsequent to FIG. 66.

FIG. 68 is a cross-sectional view of the manufacturing processsubsequent to FIG. 67.

FIG. 69 is a cross-sectional view of a laminated glass in a case where apeeling layer remains.

FIG. 70 is a view for explaining an embodiment according to the presentinvention and is a perspective view schematically illustrating a vehicleincluding a heat-generating plate. Particularly, in FIG. 70, anautomobile including a heat-generating plate is schematicallyillustrated as an example of the vehicle.

FIG. 71 is a view illustrating the heat-generating plate as viewed froma normal direction of a plate surface.

FIG. 72 is a cross-sectional view of the heat-generating plate in FIG.71.

FIG. 73 is a plan view of an exemplary shape of a reference pattern tobe referred to determine a conductive pattern of the heat-generatingplate.

FIG. 74 is an enlarged view of a part of the conductive pattern with thereference pattern illustrated in FIG. 73.

FIG. 75 is a view for explaining an action of the conductive pattern.

FIG. 76 is a view for explaining an example of a manufacturing methodfor the heat-generating plate.

FIG. 77 is a view for explaining an example of the manufacturing methodfor the heat-generating plate.

FIG. 78 is a view for explaining an example of the manufacturing methodfor the heat-generating plate.

FIG. 79 is a view for explaining an example of the manufacturing methodfor the heat-generating plate.

FIG. 80 is a view for explaining an example of the manufacturing methodfor the heat-generating plate.

FIG. 81 is a view for explaining an example of the manufacturing methodfor the heat-generating plate.

FIG. 82 is a view for explaining an example of the manufacturing methodfor the heat-generating plate.

FIG. 83 is a view for explaining a modification of the manufacturingmethod for the heat-generating plate.

FIG. 84 is a view for explaining the modification of the manufacturingmethod for the heat-generating plate.

FIG. 85 is a view for explaining the modification of the manufacturingmethod for the heat-generating plate.

FIG. 86 is a view for explaining the modification of the manufacturingmethod for the heat-generating plate.

FIG. 87 is a view for explaining the modification of the manufacturingmethod for the heat-generating plate.

FIG. 88 is a view for explaining another modification of themanufacturing method for the heat-generating plate.

FIG. 89 is a view for explaining another modification of themanufacturing method for the heat-generating plate.

FIG. 90 is a plan view illustrating a modification of the referencepattern.

FIG. 91 is an enlarged view of a part of the conductive pattern with thereference pattern illustrated in FIG. 90.

FIG. 92 is a diagram for explaining the related art.

DESCRIPTION OF EMBODIMENTS

The actions and advantages of the present invention described above willbe clarified from the following embodiments. The present invention willbe described based on the forms illustrated in the drawings. However,the present invention is not limited to these embodiments. It should benoted that the size and the shape of each member in the drawings may beexaggerated or deformed for easy understanding.

First Embodiment

FIG. 1(a) is a view for explaining one embodiment and is a conceptualview of an electrical heating glass 10 in a plan view. FIG. 1(b) is anenlarged view of a portion indicated by Ia in FIG. 1(a), and an enlargedview of a heat-generating conducting body 22L which is an example of aheat-generating conducting body 22 is illustrated. FIG. 1(c) is anenlarged view of a portion indicated by Ia in FIG. 1(a), and an enlargedview of a heat-generating conducting body 22M which is another exampleof the heat-generating conducting body 22 is illustrated. FIG. 2 is across-sectional view taken along a line II-II illustrated in FIG. 1 andis a view for explaining a layer structure along a thickness directionof the electrical heating glass 10. Such an electrical heating glass 10is, for example, included in an automobile as a windshield of anautomobile. In addition, the electrical heating glass 10 can be used asa window in a place having a so-called glass window, for example, awindow of a vehicle such as a train, an aircraft, and a ship, includingthe automobile, and a window of a building.

As can be found from FIGS. 1 and 2, the electrical heating glass 10 hasa plate-like shape as a whole, and a plurality of layers is laminatedalong the thickness direction (Z-axis direction in FIGS. 1 and 2). Morespecifically, as illustrated in the cross-sectional view in FIG. 2, theelectrical heating glass 10 according to the present embodiment includesa first panel 11, an adhesive layer 12, a heating electrode device 20,an adhesive layer 14, and a second panel 15. Each component will bedescribed below.

The first panel 11 and the second panel 15 are plate-like members havingtranslucency, that is, transparent plate-like members and are arrangedsubstantially in parallel to each other with an interval between platesurfaces arranged to face to each other. The electrical heating glass 10has a so-called double panel structure. Here, the plate surfaceindicates two planes that are parallel to the XY plane and face to eachother among the surfaces of the first panel 11 and the second panel 15in FIG. 2. A base material layer 24 and the heating electrode device 20are partially arranged between the first panel 11 and the second panel15, and the base material layer 24 and the heating electrode device 20are integrated with the adhesive layers 12 and 14. The first panel 11and the second panel 15 can be formed of a plate glass. For thesepanels, the same plate glass can be used as that used for a windownormally provided in a facility (for example, vehicle and building) towhich the electrical heating glass 10 is applied. For example, sheetglass, float plate glass, reinforced plate glass, partial plate glass,and the like made of soda-lime glass (blue plate glass), borosilicateglass (white plate glass), quartz glass, soda glass, and potassium glasscan be exemplified. In addition, the panels may have athree-dimensionally curved bent portion as necessary. However, the panelis not necessarily formed of a glass plate, and may be a resin platemade of a resin such as an acrylic resin or a polycarbonate resin.However, from the viewpoint of weather resistance property, heatresistance property, transparence, and the like, it is preferable thatthe plate be a plate glass. Although thicknesses of the first panel 11and the second panel 15 are not particularly limited, the thicknessesare equal to or more than 1.5 mm and equal to or less than 5 mm ingeneral.

The adhesive layer 12 is a layer formed of an adhesive laminated on thesurface of the first panel 11 on the side of the second panel 15 andbonds the base material layer 24 to the first panel 11. Although theadhesive is not particularly limited, a polyvinyl butyral resin can beused from the viewpoint of adhesiveness, weather resistance property,heat resistance property, and the like. Although the thickness of theadhesive layer 12 is not particularly limited, the thickness is equal toor more than 0.2 mm and equal to or less than 1.0 mm in general.

The heating electrode device 20 generates heat by being energized andheats the electrical heating glass 10. In FIG. 3, a perspective view ofa part of the heating electrode device 20 is illustrated. As can befound from FIGS. 1 to 3, in the present embodiment, the heatingelectrode device 20 includes bus bar electrodes 21, the heat-generatingconducting body 22, a power supply connecting wire 23, and the basematerial layer 24. For convenience of explanation, the base materiallayer 24 will be described first.

The base material layer 24 is a layer, having one surface on which thebus bar electrodes 21 and the heat-generating conducting body 22 of theheating electrode device 20 are particularly arranged, that functions asa base material of the bus bar electrodes 21 and the heat-generatingconducting body 22. The base material layer 24 is a transparentplate-like member and is formed of a resin. As the resin for forming thebase material layer 24, although any resin may be used as long as theresin can transmit light with a wavelength in a visible light wavelengthband (380 nm to 780 nm), a thermoplastic resin can be preferably used.As the thermoplastic resin, for example, a polyester resin such aspolyethylene terephthalate, polyethylene naphthalate, and amorphouspolyethylene terephthalate (A-PET), a polyolefin resin such aspolyethylene, polypropylene, polymethyl pentene, cyclic polyolefine, anacrylic resin such as polymethyl methacrylate, a cellulose resin such astriacetylcellulose (cellulose triacetate), a polycarbonate resin, astyrene resin such as polystyrene and acrylonitrile-styrene copolymer,and polyvinyl chloride can be exemplified. In particular, an acrylicresin and polyvinyl chloride are preferable since an acrylic resin andpolyvinyl chloride are excellent in etching resistance, weatherresistance property, and light resistance property. The thickness of thebase material layer 24 is equal to or more than 20 μm and equal to orless than 300 μm in general. A uniaxially or biaxially stretched resinlayer is used as a resin layer forming the base material layer 24 asnecessary.

In the present embodiment, the bus bar electrodes 21 include a first busbar electrode 21 a and a second bus bar electrode 21 b. Each of thefirst bus bar electrode 21 a and the second bus bar electrode 21 b has aband-like shape extending in one direction (X axis direction in FIG. 1),the first bus bar electrode 21 a and the second bus bar electrode 21 bare arranged to be extended toward the same direction (substantiallyparallel) with an interval. The first bus bar electrode 21 a and thesecond bus bar electrode 21 b can have a known form, and the width ofeach of the band-like electrodes is equal to or more than 3 mm and equalto or less than 15 mm in general.

The heat-generating conducting body 22 extends and is arranged along adirection intersecting with both bus bar electrodes 21 a and 21 b(Y-axis direction in FIG. 1) so as to connect the first bus barelectrode 21 a to the second bus bar electrode 21 b. The first bus barelectrode 21 a and the second bus bar electrode 21 b are electricallyconnected to each other with the heat-generating conducting body 22. Theheat-generating conducting body 22 generates heat by being energized.The plurality of heat-generating conducting bodies 22 is arranged alongthe longitudinal direction of the first bus bar electrode 21 a and thesecond bus bar electrode 21 b (X axis direction in FIG. 1).

The heat-generating conducting body 22 has the following shape. FIG. 4is an enlarged view of a portion indicated by IV in FIG. 2. Regarding across section of the heat-generating conducting body 22 according to thepresent embodiment perpendicular to a direction in which theheat-generating conducting body 22 extends, when it is assumed that alength of a longer side of two sides parallel to a direction in whichthe plurality of heat-generating conducting bodies 22 is arranged (sidehaving contact with base material layer 24 in the present embodiment) bea width W_(B) and a length of the heat-generating conducting body 22 ina direction perpendicular to the direction in which the plurality ofheat-generating conducting bodies 22 is arranged (thickness direction ofheating electrode device 20, Z axis direction in FIG. 2) be a thicknessH, (H/W_(B))>1.0 is satisfied. That is, the thickness H is larger thanthe width W_(B). According to this, while reducing the width of theheat-generating conducting body 22 which causes visual recognition ofthe heat-generating conducting body 22, a cross sectional area of theheat-generating conducting body 22 can be larger by setting thethickness to be larger than the width. Therefore, the heat-generatingconducting body can be hardly recognized in a visual way while having ahigh output (high heat generation performance).

It is preferable that other parts be formed as follows while satisfyingthe above conditions. In FIG. 4, reference numerals are applied forexplanation. It is preferable that an interval B between the adjacentheat-generating conducting bodies 22 illustrated as B in FIG. 4 be equalto or more than 0.5 mm and equal to or less than 5.00 mm. Morepreferably, the interval B is equal to or more than 1.0 mm, and furtherpreferably, the interval B is equal to or more than 1.25 mm. In thecross section, when it is assumed that the width be W_(B) and the lengthof the side opposite to W_(B) be W_(T), it is preferable thatW_(B)>W_(T), 3 μm≤W_(B)≤15 μm, and 1 μm≤W_(T)≤12 μm are satisfied. Thecross section is a surface that is cut to have a minimum cross sectionalarea in that portion. In a case where unevenness is formed on thesurface of the heat-generating conducting body 22, a cross section withthe minimum area including the unevenness is considered. Furthermore, itis preferable that the thickness H of the heat-generating conductingbody 22 be equal to or larger than 5 μm and equal to or less than 30 μm.

In addition, it is preferable that a pitch P between the adjacentheat-generating conducting bodies 22 be equal to or more than 0.5 mm andequal to or less than 5.00 mm. When the pitch P is less than 0.5 mm, theheat-generating conducting bodies 22 are arranged close to each otherand easily visually recognized. Preferably, the pitch P is equal to ormore than 1.0 mm, and more preferably, the pitch P is equal to or morethan 1.25 mm. On the other hand, if the pitch P is more than 5.00 mm,uniform heating performance may be deteriorated.

In the thickness direction of the heating electrode device 20, when itis assumed that a surface area of one surface (base material layer 24 inthe present embodiment) of the heat-generating conducting body 22 perlength of 0.01 m in a plan view be S_(B) and a surface area of the othersurface per length of 0.01 m in a plan view be S_(T), it is preferableto satisfy 0 μm²<S_(B)−S_(T)≤30000 μm². Here, as indicated by thereference L in FIG. 1, the “length” indicates a distance from one end ofthe extending heat-generating conducting body 22 to the other end. Morepreferably, 0 μm²<S_(B)−S_(T)≤15000 μm² is satisfied. According to this,when it is assumed that a length of the heat-generating conducting body22 in a direction along the surface of the base material layer 24(horizontal direction in FIG. 4, X axis direction in FIG. 2) be thewidth of the heat-generating conducting body 22, a large cross sectionalarea can be obtained while suppressing an increase in the width evenwhen the heat-generating conducting body is produced by etching.Although it is ideal if a rectangular shape (rectangle) can be produced,it is difficult to produce the rectangle by etching due to nature of aso-called side edge.

As a conductive material forming the heat-generating conducting body 22,for example, a band-shaped member pattern formed by etching a metal suchas tungsten, molybdenum, nickel, chromium, copper, silver, platinum, andaluminum, and an alloy such as a nickel-chromium alloy, bronze, andbrass including these metals can be exemplified. To further enhanceinvisibility of the heat-generating conducting body 22, on any one ormore of four surfaces around each heat-generating conducting body 22(for example, top surface in FIG. 4 (surface with width W_(T)), lowersurface (surface with width W_(B)), right surface, and left surface),more preferably, on four surfaces, a light-absorbing dark color layercan be laminated. As such a dark color layer, a layer formed of amaterial such as copper oxide (CuO), copper nitride, ferrosoferric oxide(Fe3O4), and copper-cobalt alloy can be formed by a method such as vapordeposition, sputtering, electrolyzation, or electroless plating ashaving a thickness of about 0.01 μm to 1 μm. As a dark color, inaddition to black, a color with low intensity such as gray, brown, darkblue, dark green, dark purple, and dark red is appropriately selected. Ahue and intensity of the dark color can be selected based on a material,a film thickness, and a crystal grain size of the dark color layer.

In the present embodiment, as indicated by the reference numeral 22L inthe enlarged view of the heat-generating conducting body 22 illustratedin FIG. 1(b), the heat-generating conducting body 22 is linearly formed,and the heat-generating conducting bodies 22 form a parallel lineargroup. However, in addition to this, the heat-generating conducting body22 may be formed in a band-like shape and in a wavy line shape asindicated by the reference numeral 22M in the enlarged view of theheat-generating conducting body 22 illustrated in FIG. 1(c).

As can be found from FIG. 1(a), the power supply connecting wire 23connects a power supply 40 between the first bus bar electrode 21 a andthe second bus bar electrode 21 b. The power supply 40 is notparticularly limited as long as the power supply can supply powernecessary for dissolving or evaporating water droplets (frosting),freezing (frosting) and the like, any known direct current or alternatecurrent power supply having an appropriate voltage, current, orfrequency may be used. In a case where the electrical heating glass 10is applied to an automobile, as the power supply 40, for example, abattery such as a lead storage battery and a lithium ion storage batteryprovided in the automobile can be used as a DC power supply. At thistime, for example, a positive electrode of the battery can be connectedto the second bus bar electrode 21 b, and a negative electrode can beconnected to the first bus bar electrode 21 a. Naturally, a dedicatedpower supply (battery cell, generator, and the like) may be usedseparately. Furthermore, in a case of a railway vehicle powered by anelectric motor, DC or AC power supplied from an overhead wire can beused by appropriately converting the power into an appropriate voltageor current. The power supply connecting wire 23 may have a knownstructure.

The adhesive layer 14 bonds the base material layer 24 including the busbar electrodes 21 and the heat-generating conducting bodies 22 to thesecond panel 15. The adhesive layer 14 can have the same structure asthe adhesive layer 12.

With the above components, the electrical heating glass 10 is asfollows. As can be found from FIG. 2, the adhesive layer 12 is laminatedon one surface of the first panel 11, and the base material layer 24 islaminated on the first panel 11 via the adhesive layer 12. The heatingelectrode device 20 is arranged on a surface of the base material layer24 opposite to the surface on which the adhesive layer 12 is arranged.Although the second panel 15 is arranged on the surface of the heatingelectrode device 20 opposite to the surface on which the base materiallayer 24 is arranged, the adhesive layer 14 is arranged to fill a spacebetween the base material layer 24 and the heating electrode device 20and the second panel 15. Accordingly, the second panel 15 is laminatedon the base material layer 24 and the heating electrode device 20.

Such a heating electrode device 20 and the electrical heating glass 10including the same can be manufactured, for example, as follows. FIGS.5(a) to 5(d) are views for explanation.

First, as illustrated in FIG. 5(a), a metal foil 22′ is bonded to andlaminated on the base material layer 24 formed of a resin film via anadhesive layer to manufacture a laminate. Next, as illustrated in FIG.5(b), a photosensitive resist layer 80 is applied and formed on themetal foil 22′ of the laminate.

Next, a photomask is prepared that has a desired pattern, for example, alight-shielding pattern based on a plan view pattern of the heatingelectrode device 20 including the heat-generating conducting bodies 22and the bus bar electrodes 21 a and 21 b arranged in a pattern in whichband-like linear lines are arranged in parallel as illustrated in FIG.1(b). Then, the photomask is placed in close contact with thephotosensitive resist layer 80. Then, the photosensitive resist layer 80is exposed to ultraviolet rays through the photomask, and the photomaskis removed, and sequentially, the photosensitive resist layer which isnot exposed is dissolved and removed by known developing processing, anda resist pattern layer 80′ having a shape matching a desired pattern 80a is formed on the metal foil 22′ as illustrated in FIG. 5(c). Here, inFIG. 5(c), positions and sizes of the heat-generating conducting bodies22 to be formed are indicated by broken lines with a light color as areference. As can be found from FIG. 5(c), this example is formed sothat a distance from an edge of the resist pattern 80 a formed on theresist pattern layer 80 c to an edge of the heat-generating conductingbody 22 to be formed is C. It is preferable that the distance C be equalto or longer than 5 μm and equal to or shorter than 30 μm. As a result,the heat-generating conducting body 22 having the above form can beobtained by etching.

Next, etching (corrosion) processing using corrosive liquid is performedon the laminate from the resist pattern layer 80′, and the resistpattern layer 80′ and the metal foil 22′ are corroded and removed asillustrated in FIG. 5(d). Then, the resist pattern layer is dissolvedand removed (remove coating). As described above, a laminated structurein which the heat-generating conducting bodies 22 and the bus barelectrodes 21 a and 21 b with a predetermined pattern having a plan viewshape in FIG. 1(a) and a cross section shape in FIG. 2 are formed on thebase material layer 24 is manufactured.

Next, the first panel 11, the adhesive layer 12, the laminated structureincluding the base material layer 24 and the heating electrode device20, the adhesive layer 14, and the second panel 15 are laminated in thisorder, and the plurality of layers is bonded, laminated, and integratedto each other. According to the above process, the electrical heatingglass 10 illustrated in the plan view in FIG. 1(a) and thecross-sectional view in FIG. 2 is manufactured.

According to the electrical heating glass 10 described above, aheat-generating conducting body of which a shape of the cross section isclose to a rectangle can be obtained by etching, the thickness and thecross sectional area can be increased while the length in the widthdirection is reduced than a heat-generating conducting body having atrapezoidal cross section in which a difference between an upper baseand a lower base is large.

The electrical heating glass 10 is used and acts, for example, asfollows. Here, as an example, a case where the electrical heating glass10 is applied to a front panel of an automobile will be described. Thatis, in the embodiment in FIG. 1, the electrical heating glass 10 isarranged at a position of the front panel of the automobile, and thepower supply connecting wire 23 is connected to the power supply 40 viaa switch 50 at this time, and the heat-generating conducting body 22 canbe heated via the bus bar electrodes 21. In the present embodiment, abattery provided in the automobile is used as the power supply 40. Whenthe switch 50 is closed, the power supply 40 supplies a current. Sincegenerated Joule heat of the heat-generating conducting body 22 heats thefirst panel 11 and the second panel 15 of the heat-generating conductingbody 22, the temperature of the electrical heating glass 10 thatfunctions as a front panel increases, and this eliminates freezing andfogging. In the present embodiment, since the heat generation can befacilitated by having a large cross section of the heat-generatingconducting body 22, freezing and fogging can be eliminated earlier.

Second Embodiment

FIG. 6(a) is a view for explaining one embodiment and is a conceptualview of an electrical heating glass 110 in a plan view. FIG. 6(b) is anenlarged view of a portion indicated by Ia in FIG. 6(a), and an enlargedview of a heat-generating conducting body 122 which is an example of aheat-generating conducting body 122 is illustrated. FIG. 7 is across-sectional view taken along a line VII-VII illustrated in FIG. 6and is a view for explaining a layer structure along a thicknessdirection of the electrical heating glass 110. Such an electricalheating glass 110 is, for example, included in an automobile as awindshield of an automobile. In addition, the electrical heating glass10 can be used as a window in a place having a so-called glass window,for example, a window of a vehicle such as a train, an aircraft, and aship, including the automobile, and a window of a building.

As can be found from FIGS. 6 and 7, the electrical heating glass 110 hasa plate-like shape as a whole, and a plurality of layers is laminatedalong the thickness direction (Z-axis direction in FIGS. 6 and 7). Morespecifically, as illustrated in the cross-sectional view in FIG. 7, theelectrical heating glass 110 according to the present embodimentincludes a first panel 111, an adhesive layer 112, a heating electrodedevice 120, an adhesive layer 114, and a second panel 115. Eachcomponent will be described below.

The first panel 111 and the second panel 115 are plate-like membershaving translucency, that is, transparent plate-like members and arearranged in substantially parallel to each other with an intervalbetween plate surfaces facing to each other. The electrical heatingglass 110 has a so-called double panel structure. Here, the platesurface indicates two planes that are parallel to the XY plane and faceto each other among the surfaces of the first panel 111 and the secondpanel 115 in FIG. 7. A part of the heating electrode device 120 isarranged between the first panel 111 and the second panel 115, and theheating electrode device 120 and the panels are integrated with theadhesive layers 112 and 114. The first panel 111 and the second panel115 can be formed of a plate glass. For these panels, the same plateglass can be used as that used for a window normally provided in afacility (for example, vehicle and building) to which the electricalheating glass 110 is applied. For example, sheet glass, float plateglass, reinforced plate glass, partial plate glass, and the like made ofsoda-lime glass (blue plate glass), borosilicate glass (white plateglass), quartz glass, soda glass, and potassium glass can beexemplified. In addition, the panels may have a three-dimensionallycurved bent portion as necessary. However, the panel is not necessarilyformed of a glass plate, and may be a resin plate made of a resin suchas an acrylic resin or a polycarbonate resin. However, from theviewpoint of weather resistance property, heat resistance property,transparence, and the like, it is preferable that the plate be a plateglass. Although thicknesses of the first panel 111 and the second panel115 are not particularly limited, the thicknesses are equal to or morethan 1.5 mm and equal to or less than 5 mm in general.

The adhesive layer 112 is a layer formed of an adhesive laminated on thesurface of the first panel 111 on the side of the second panel 115 andbonds the base material layer 124 to the first panel 111. Although theadhesive is not particularly limited, a polyvinyl butyral resin can beused from the viewpoint of adhesiveness, weather resistance property,heat resistance property, and the like. Although the thickness of theadhesive layer 112 is not particularly limited, the thickness is equalto or more than 0.2 mm and equal to or less than 1.0 mm in general.

The heating electrode device 120 generates heat by being energized andheats the electrical heating glass 110. In FIG. 8, a perspective view ofa part of the heating electrode device 120 is illustrated. As can befound from FIGS. 6 to 8, in the present embodiment, the heatingelectrode device 120 includes bus bar electrodes 121, theheat-generating conducting body 122, a power supply connecting wire 123,and the base material layer 124. For convenience of explanation, thebase material layer 124 will be described first.

The base material layer 124 is a layer, having one surface on which thebus bar electrodes 121 and the heat-generating conducting body 122 ofthe heating electrode device 120 are particularly arranged, thatfunctions as a base material of the bus bar electrodes 121 and theheat-generating conducting body 122. The base material layer 124 is atransparent plate-like member and is formed of a resin. As a resin forforming the base material layer 124, although any resin may be used aslong as the resin can transmit light with a wavelength in a visiblelight wavelength band (380 nm to 780 nm), a thermoplastic resin can bepreferably used. As a thermoplastic resin, for example, a polyesterresin such as polyethylene terephthalate, polyethylene naphthalate, andamorphous polyethylene terephthalate (A-PET), a polyolefin resin such aspolyethylene, polypropylene, polymethyl pentene, cyclic polyolefine, anacrylic resin such as polymethyl methacrylate, a cellulose resin such astriacetylcellulose (cellulose triacetate), a polycarbonate resin, astyrene resin such as polystyrene and acrylonitrile-styrene copolymer,and polyvinyl chloride can be exemplified. In particular, an acrylicresin and polyvinyl chloride are preferable since an acrylic resin andpolyvinyl chloride are excellent in etching resistance, weatherresistance property, and light resistance property. The thickness of thebase material layer 124 is equal to or more than 20 μm and equal to orless than 300 μm in general. A uniaxially or biaxially stretched resinlayer is used as a resin layer forming the base material layer 124 asnecessary.

In the present embodiment, the bus bar electrodes 121 include a firstbus bar electrode 121 a and a second bus bar electrode 121 b. Each ofthe first bus bar electrode 121 a and the second bus bar electrode 121 bhas a band-like shape extending in one direction (X axis direction inFIG. 6), the first bus bar electrode 121 a and the second bus barelectrode 121 b are arranged to be extended toward the same direction(substantially parallel) with an interval. The first bus bar electrode121 a and the second bus bar electrode 121 b can have a known form, andthe width of each of the band-like electrodes is equal to or more than 3mm and equal to or less than 15 mm in general.

The heat-generating conducting body 122 extends and is arranged along adirection intersecting with both bus bar electrodes 121 a and 21 b(Y-axis direction in FIG. 6) so as to connect the first bus barelectrode 121 a to the second bus bar electrode 121 b. The first bus barelectrode 121 a and the second bus bar electrode 121 b are electricallyconnected to each other with the heat-generating conducting body 122.The heat-generating conducting body 122 generates heat by beingenergized. The plurality of heat-generating conducting bodies 122 isarranged along the longitudinal direction of the first bus bar electrode121 a and the second bus bar electrode 121 b (X axis direction in FIG.6).

The heat-generating conducting body 122 has the following shape. Asillustrated in FIG. 6, when it is assumed that an interval between thefirst bus bar electrode 121 a and the second bus bar electrode 121 b beD (mm) and a length of a single heat-generating conducting body 122between the first bus bar electrode 121 a and the second bus barelectrode 121 b be L (mm), that is, when it is assumed that a distancebetween both ends of the heat-generating conducting body 122 be D (mm)and the length along the heat-generating conducting body 122 between theboth ends be L (mm), 1.02·D≤L<1.50·D is satisfied. As a result, a formto prevent a beam of light can be formed, and unnecessary increase inthe resistance of the heat-generating conducting body can be prevented,and accordingly, a heating value can be maintained at a high level. Thatis, it is possible to prevent a beam of light and to efficiently removefrost and fogging.

Although a specific form of the heat-generating conducting body is notparticularly limited as long as the above condition is satisfied, tomore reliably prevent a beam of light, it is preferable that theheat-generating conducting body 122 has a wavy form in a plan view(point of sight in FIG. 6).

Furthermore, it is preferable that the heat-generating conducting body122 be configured as follows. FIG. 9 is an enlarged view of a portionindicated by IX in FIG. 7. Regarding the heat-generating conducting body122, in the thickness direction of the heating electrode device 120,when it is assumed that a surface area of one surface of (base materiallayer 124 in the present embodiment) the heat-generating conducting body122 per length of 0.01 m in a plan view be S_(B) (μm²) and a surfacearea of the other surface per length of 0.01 m in a plan view be S_(T)(μm²), it is preferable to satisfy 0 μm²<S_(B)−S_(T)≤30000 μm². Here,the “length” is a distance between one end and the other end when acertain portion of the extending heat-generating conducting body 122having a length of 0.01 m is extracted. More preferably, 0μm²<S_(B)−S_(T)≤15000 μm² is satisfied. Accordingly, when theheat-generating conducting body 122 is produced with a width with whichthe heat-generating conducting body 122 cannot be visually recognized,the cross sectional area can be large, and a higher output (heatingvalue) can be obtained. Although it is ideal if a rectangular shape(rectangle) can be produced, it is difficult to produce the rectangle byetching due to nature of a so-called side edge.

It is preferable that other parts be formed as follows while satisfyingthe above conditions. In FIG. 9, reference numerals are applied forexplanation. It is preferable that an interval between the adjacentheat-generating conducting bodies 122 illustrated as B in FIG. 9 beequal to or more than 0.5 mm and equal to or less than 5.00 mm. Morepreferably, the interval is equal to or more than 1.0 mm, and furtherpreferably, the interval B is equal to or more than 1.25 mm. In thecross section, when it is assumed that the width be W_(B) (μm) and thelength of the side opposite to W_(B) be W_(T) (μm), it is preferablethat W_(B)>W_(T), 3 μm≤W_(B)≤15 μm, and 1 μm≤W_(T)≤12 μm be satisfied.The cross section is a surface that is cut to have a minimum crosssectional area in that portion. In a case where unevenness is formed onthe surface of the heat-generating conducting body 122, a cross sectionwith the minimum area including the unevenness is considered.Furthermore, it is preferable that the thickness H (μm) of theheat-generating conducting body 122 be equal to or larger than 5 μm andequal to or less than 30 μm.

In addition, it is preferable that a pitch P (mm) between the adjacentheat-generating conducting bodies 122 be equal to or more than 0.5 mmand equal to or less than 5.00 mm. When the pitch P (mm) is less than0.5 mm, the heat-generating conducting bodies 122 are arranged close toeach other and easily visually recognized. Preferably, the pitch P (mm)is equal to or more than 1.0 mm, and more preferably, the pitch P (mm)is equal to or more than 1.25 mm. On the other hand, if the pitch P (mm)is more than 5.00 mm, uniform heating performance may be deteriorated.

As a conductive material forming the heat-generating conducting body122, for example, a band-shaped member pattern formed by etching a metalsuch as tungsten, molybdenum, nickel, chromium, copper, silver,platinum, and aluminum, and an alloy such as a nickel-chromium alloy,bronze, and brass including these metals can be exemplified.

As can be found from FIG. 6(a), the power supply connecting wire 123connects a power supply 140 between the first bus bar electrode 121 aand the second bus bar electrode 121 b. The power supply 140 is notparticularly limited as long as the power supply can supply powernecessary for dissolving or evaporating water droplets (fogging),freezing (frosting) and the like, any known direct current or alternatecurrent power supply having an appropriate voltage, current, orfrequency may be used. In a case where the electrical heating glass 110is applied to an automobile, for example, as the power supply 140, abattery such as a lead storage battery and a lithium ion storage batteryprovided in the automobile can be used as a DC power supply. At thistime, for example, a positive electrode of the battery can be connectedto the second bus bar electrode 121 b, and a negative electrode can beconnected to the first bus bar electrode 121 a. Naturally, a dedicatedpower supply (battery cell, generator, and the like) may be usedseparately. Furthermore, in a case of a railway vehicle powered by anelectric motor, DC or AC power supplied from an overhead wire can beused by appropriately converting the power into an appropriate voltageor current. The power supply connecting wire 123 may have a knownstructure.

The adhesive layer 114 bonds the base material layer 124 including thebus bar electrodes 121 and the heat-generating conducting bodies 122 tothe second panel 115. The adhesive layer 114 can have the same structureas the adhesive layer 112.

With the above components, the electrical heating glass 110 is formed asfollows. As can be found from FIG. 7, the adhesive layer 112 islaminated on one surface of the first panel 111, and the base materiallayer 124 is laminated on the first panel 111 via the adhesive layer112. The heating electrode device 120 is arranged on a surface of thebase material layer 124 opposite to the surface on which the adhesivelayer 112 is arranged. Although the second panel 115 is arranged on thesurface of the heating electrode device 120 opposite to the surface onwhich the base material layer 124 is arranged, the adhesive layer 114 isarranged to fill a space between the base material layer 124 and theheating electrode device 120 and the second panel 115. Accordingly, thesecond panel 115 is laminated on the base material layer 124 and theheating electrode device 120.

Such a heating electrode device 120 and the electrical heating glass 110including the same can be manufactured, for example, as follows. FIGS.10(a) to 10(d) are views for explanation.

First, as illustrated in FIG. 10(a), a metal foil 122′ is bonded to andlaminated on the base material layer 124 formed of a resin film via anadhesive layer to manufacture a laminate. Next, as illustrated in FIG.10(b), a photosensitive resist layer 180 is applied and formed on themetal foil 122′ of the laminate.

Next, a photomask is prepared that has a light-shielding pattern basedon a plan view pattern of the heat-generating conducting bodies 122 andthe bus bar electrodes 121 which is a desired pattern. Then, thephotomask is placed in close contact with the photosensitive resistlayer 180. Then, the photosensitive resist layer 180 is exposed toultraviolet rays through the photomask, and the photomask is removed,and sequentially, the photosensitive resist layer which is not exposedis dissolved and removed by known developing processing, and a resistpattern layer 180′ having a shape matching a desired pattern 180 a isformed on the metal foil 122′ as illustrated in FIG. 10(c). Here, inFIG. 10(c), positions and sizes of the heat-generating conducting bodies122 to be formed are indicated by broken lines with a light color as areference. As can be found from FIG. 10(c), this example is formed sothat a distance from an edge of the resist pattern 180 a formed on theresist pattern layer 180 c to an edge of the heat-generating conductingbody 122 to be formed is C (μm). It is preferable that the distance C beequal to or longer than 5 μm and equal to or shorter than 30 μm. As aresult, the heat-generating conducting body 122 having the above formcan be obtained by etching.

Next, etching (corrosion) processing using corrosive liquid is performedon the laminate from the resist pattern layer 180′, and the resistpattern layer 180′ and the metal foil 122′ are corroded and removed asillustrated in FIG. 10(d). Then, the resist pattern layer is dissolvedand removed (remove coating). As described above, a laminated structurein which the heat-generating conducting bodies 122 and the bus barelectrodes 121 a and 21 b with a predetermined pattern having a planview shape in FIG. 6(a) and a cross section shape in FIG. 7 are formedon the base material layer 124 is manufactured.

In the present embodiment, since the cross section of theheat-generating conducting body 122 is defined as described above, theheat-generating conducting body 122 can be formed with highproductivity.

Next, the adhesive layer 114 and the second panel 115 are laminated onthe laminated structure, including the first panel 111, the adhesivelayer 112, and the heating electrode device 120, in this order, and theplurality of layers is bonded, laminated, and integrated with eachother. According to the above process, the electrical heating glass 110illustrated in the plan view in FIG. 6(a) and the cross-sectional viewin FIG. 7 is manufactured.

According to the manufacturing method for the electrical heating glass110 described above, a heat-generating conducting body of which a shapeof the cross section is close to a rectangle can be obtained by etching,the thickness and the cross sectional area can be increased while thelength in the width direction is reduced than a heat-generatingconducting body having a trapezoidal cross section in which a differencebetween an upper base and a lower base is large.

The electrical heating glass 110 is used and acts, for example, asfollows. Here, as an example, a case where the electrical heating glass110 is applied to a front panel of an automobile will be described. Thatis, in the embodiment in FIG. 6, the electrical heating glass 110 isarranged at a position of the front panel of the automobile, and thepower supply connecting wire 123 is connected to the power supply 140via a switch 150 at this time, and the heat-generating conducting body122 can be heated via the bus bar electrodes 121. In the presentembodiment, a battery provided in the automobile is used as the powersupply 140. When the switch 150 is closed, the power supply 140 suppliesa current. Since generated Joule heat of the heat-generating conductingbody 122 heats the first panel 111 and the second panel 115 of theheat-generating conducting body 122, the temperature of the electricalheating glass 110 that functions as a front panel increases, and thiseliminates freezing and fogging. In the present embodiment, since it ispossible to prevent a beam of light and facilitate heat generation bysetting the length of the heat-generating conducting body 122 to alength within a predetermined range, freezing and fogging can beefficiently eliminated while preventing a beam of light.

EXAMPLE

In the example, a defrosting time and a beam of light are evaluated bychanging a ratio of a length L (mm) of the heat-generating conductingbody along the heat-generating conducting body relative to a distance D(mm) between ends of the heat-generating conducting body.

An electrical heating glass is produced as the example of the electricalheating glass 110. At this time, a vertical length and a horizontallength of a heat generating area are 300 mm, and a nickel electrode witha thickness of 50 μm and a width of 20 mm is provided on each end. It isassumed that the thickness of each heat-generating conducting body be 12μm and a pitch between adjacent heat-generating conducting bodies be1.25 mm. Table 1 illustrates a relationship between D and L in eachexample.

A test regarding a beam of light has been carried out as follows. First,the produced electrical heating glass is irradiated with light from alight source ((light of automobile manufactured by SUBARU CORPORATION,FORESTER (registered trademark)) arranged at a position 4 m separatedfrom the electrical heating glass. At this time, the electrical heatingglass is placed with an inclination of 60 degrees with respect to thevertical direction. Subsequently, the electrical heating glass is viewedfrom an opposite side of the light source across the electrical heatingglass and from a position that is 50 cm separated from the electricalheating glass. In a case where a beam of light is generated, B iswritten, and in a case where a beam of light is not generated, A iswritten.

On the other hand, a test regarding defrosting (defroster performancetest) has been carried out as conforming to JIS D 4501-1994, and aspecimen is placed with an inclination with 60 degrees with respect tothe vertical direction as in the test regarding the beam of light. In astate where the electrical heating glass is covered with ice, a timefrom the start of energization to a time when the ice is eliminated froman entire surface of the electrical heating glass is measured. Here, avoltage applied to the electrical heating glass is 4.2 V.

In Table 1, in addition to the length of the heat-generating conductingbody, the defrosting time and whether the beam of light is generated areillustrated.

TABLE 1 LENGTH OF HEAT- GENERATING DEFROSTING BEAM CONDUCTING TIME OFBODY (mm) (minute) LIGHT EXAMPLE 1 1.02 · D 4.1 A EXAMPLE 2 1.10 · D 4.4A EXAMPLE 3 1.30 · D 4.9 A COMPARATIVE 1.00 · D 4.0 B EXAMPLE 1COMPARATIVE 1.50 · D 6.0 A EXAMPLE 2

As can be found from Table 1, by satisfying the present embodiment, thebeam of light can be prevented, and the preferable defrosting time canbe obtained.

Third Embodiment

In the following description, terms of “plate”, “sheet”, and “film” arenot distinguished from each other based on a difference in the name. Forexample, the term “sheet” is a concept that may include a member whichcan be called “plate” or “film”, and these members are not necessarilydistinguished from each other only based on the difference in the name.In addition, terms used herein for specifying shapes and geometricconditions and degrees thereof (for example, terms including“identical”, “same”, and “equal” and other terms indicating physicalproperties such as values of lengths and angles) are not limited tostrict meanings and are interpreted as including a range of terms thatcan be expected to have a similar function.

In addition, each component illustrated in the drawing attached to thespecification has a size and a position that do not necessarily coincidewith those of a real one, and the components are illustrated asappropriately changing the scale, the dimensional ratio in the in thevertical and horizontal directions, the arrangement relationship, andthe like.

First, regarding “prevention of generation of a beam of light”,“antiglare”, and “achievement of both of prevention of generation of abeam of light and antiglare” regarding a heat-generating plate (refer toreference numeral “210” in FIG. 14) including heat-generating conductorsincluding a plurality of conductive thin wires, the findings of theinventors will be described.

<Prevention of Generation of Beam of Light>

As a result of intensive research, the inventors of the presentinvention have newly found that a thin-line heat-generating conductor(conductive thin wire) may cause a beam of light and that a beam oflight is easily generated especially in a case where a large number ofconductive thin wires are arranged in the same pattern. Generally, abeam of light is caused by diffraction of light. For example, when lightenters a transparent heat-generating plate, the incident light isdiffracted by each conductive thin wire. Particularly, diffraction lightbeams caused by conductive thin wires arranged in the same patterninterfere with each other and easily cause a beam of light that iselongated in a radial shape and can be visually recognized.

The inventors of the present invention have focused on a generationmechanism of a beam of light and have found that generation of the beamof light that can be visually recognized can be effectively prevented byirregularly arranging the plurality of conductive thin wires. That is,the inventors of the present invention have newly found that, from theviewpoints of preventing the generation of the beam of light that can bevisually recognized, “the plurality of conductive thin wires linearlyarranged in parallel” and “the plurality of conductive thin wiresarranged in the same pattern” are not preferable and that “the pluralityof conductive thin wires irregularly arranged with various curvatures ina plan view” is preferable (refer to reference numeral “230” in FIG. 15described later). In a plan view, a shape of the heat-generating plate210 including the heat-generating conductor 230 observed from a normaldirection of a front and rear surfaces of the heat-generating plate 210(Z direction in FIG. 15 to be described later), and FIG. 15 correctlyillustrates the shape of the heat-generating conductor 230 in a planview.

<About Antiglare>

In general, from a viewpoint of realizing an excellent visibility, awindow that causes a phenomenon such as glare which may interfere thefield of view is not preferable. For example, in a case where atransparent heat-generating plate is used for a vehicle window, when aso-called glare phenomenon such as dazzle or blur in which theconductive thin wire is visually recognized with sparkle in a case of aspecific combination of an incident angle and a line of sight of anobserver due to light reflection by the surface of the conductive thinwire (heat-generating conductor) occurs in light observed through thevehicle window, a field of view of a vehicle occupant such as a drivermay be impaired, and in addition, eyestrain of the vehicle occupant isincreased. Accordingly, even in a case where the “transparentheat-generating plate including the plurality of conductive thin wiresirregularly arranged with various curvatures in a plan view” describedabove is used for a window, it is required to maintain excellentvisibility by preventing a phenomenon such as glare.

Although a part of the light entering the transparent heat-generatingplate including the plurality of conductive thin wires is reflected byeach conductive thin wire, specific light reflection aspects in theconductive thin wires vary according to the shape of the cross sectionalarea of each conductive thin wire.

FIGS. 11A and 11B are diagrams for explaining a relationship between across sectional shape of the thin linear heat-generating conductor 230and a light reflection aspect. FIG. 11A illustrates an example of aheat-generating conductor 230 having a rectangular cross sectional area,and FIG. 11B illustrates an example of a heat-generating conductor 230having a non-rectangular cross sectional area. Here, the cross sectionalarea indicates a cross section obtained by cutting a heat-generatingconductor (conductive thin wire) along a direction perpendicular to anextending direction of the heat-generating conductor (conductive thinwire) (for example, direction of center line of conductive thin wire(length direction)). For example, FIGS. 17A and 17B to be describedlater illustrate the cross section of the heat-generating conductor. Inaddition, in FIGS. 17A and 17B, the extending direction is a Ydirection, and the cross sectional area has a ZX plane.

As illustrated in FIG. 11A, the cross section of each heat-generatingconductor 230 has a rectangular shape that is defined by two sides S2and S4 extending along a direction same as an incident direction L oflight and two sides S1 and S3 extending along a direction perpendicularto the incident direction L, light reflected by the side S1 in thedirection perpendicular to the incident direction L travels in adirection opposite to the incident direction L, and the other sides S2to S4 do not reflect light traveling in the incident direction L inprinciple. Therefore, if the cross sectional area of the heat-generatingconductor 230 included in the heat-generating plate has a rectangularshape, a light component reflected by the heat-generating conductor 230of the light traveling in the incident direction L does not enter andinterfere a visual field of a vehicle occupant who observes lightthrough the heat-generating plate (vehicle window).

However, in reality, it is very difficult to accurately process thecross section of the heat-generating conductor 230 into the rectangularshape, and especially, in a case where the heat-generating conductor 230is formed by etching (corrosion processing), the heat-generatingconductor 230 usually has a non-rectangular cross sectional area asillustrated in FIG. 11B by a so-called side etching phenomenon. Theheat-generating conductor 230 illustrated in FIG. 11B is common to thatin FIG. 11A in that two sides S1 (upper bottom) and S3 (lower bottom)extending along a direction perpendicular to the incident direction L ofthe light are included. However, extending directions of the sides S2(first inclined portion) and S4 (second inclined portion) connecting thesides S1 and S3 extending in the direction perpendicular to the incidentdirection L do not coincide with the incident direction L. That is, eachof the side S2 extending between one ends of the sides S1 and S3extending along the direction perpendicular to the incident direction Land the side S4 extending between the other ends is curved with aninclination with respect to the incident direction L. Therefore, a partof the light traveling in the incident direction L is reflected by theinclined sides (referred to as “inclined portion” below) S2 and S4 ofthe heat-generating conductor 230 and subsequently travels in variousdirections different from the original incident direction L.Particularly, actual observed light entering the heat-generating plate(vehicle window and the like) does not necessarily include only opticalcomponents for traveling in one direction, the observed light includesoptical components for travelling in various directions in most cases.Therefore, a part of the light reflected by the inclined portions S2 andS4 of the heat-generating conductor 230 may enter the visual field ofthe vehicle occupant. Such reflected light is light for traveling in adirection different from an original traveling direction, and thereflected light enters the visual field of a user (observer observingtransmitted light) at an unexpected angle and causes glare such asdazzle or blur. Therefore, the reflected light is not preferable in aviewpoint for securing excellent visibility.

The inventors of the present invention have focused on a lightreflection mechanism by the conductive thin wire and have newly foundthat glare such as dazzle or blur can be effectively prevented byadjusting a cross sectional shape of the conductive thin wire so thatthe inclined portion of each conductive thin wire has various angles asan inclination angle in the cross section. That is, if the inclinationangles of the inclined portions of the cross sectional areas of all theconductive thin wires included in the heat-generating plate are commonto each other, dazzle or blur may be emphasized in light observed by theuser through the heat-generating plate. Therefore, the inventors of thepresent invention have newly found that glare is effectively preventedby giving various angles (inclination) to the plurality of conductivethin wires in the cross section.

<Achievement of both of Prevention of Occurrence of Beam of Light andAntiglare>

In the window using the heat-generating plate, the conductive thin wireexists in the field of view of the user. However, from the viewpoint ofrealizing clear visibility, it is preferable to sufficiently thin theconductive thin wire so that the conductive thin wire is not visuallyrecognized as possible.

However, when the conductive thin wire is thinned, it is difficult toapply angle variations to the inclination angle of the inclined portionof the cross sectional area of the conductive thin wire. That is, torealize a gentle inclination by reducing the inclination angle of theinclined portion of the cross sectional area in the extremely thinconductive thin wire, for example, in the example illustrated in FIG.11B, a difference between lengths of a side S1 (upper bottom) and a sideS3 (lower bottom) is increased, and the sufficient length of the shorterside S1 (upper bottom) cannot be especially secured. When the upperbottom S1 of the cross sectional area of the conductive thin wire isextremely short, a possibility that the conductive thin wire isdisconnected due to a manufacturing error and the like is increased.

Therefore, by mixedly providing relatively thick portions and relativelythin portions in each conductive thin wire, desired angle variations canbe easily applied to the inclination angle of the inclined portion ofthe cross sectional area of each conductive thin wire. In particular, itis desirable to realize a “gentle inclination with a small inclinationangle” in the relatively thick inclined portion of the conductive thinwire and realize a “steep inclination with a large inclination angle” inthe relatively thin inclined portion of the conductive thin wire fromthe viewpoint of preventing the disconnection of the conductive thinwire.

On the other hand, regarding the plurality of conductive thin wiresarranged with various curvatures to prevent a beam of light, underconstraints on the arrangement space, the width of the conductive thinwire is easily increased in a portion with a smaller curvature and asmaller curve than a portion with a larger curvature and a larger curve.Therefore, it is preferable to vary the inclination angle of theinclined portion by making the inclination of the inclined portion ofthe cross sectional area be gentle by thickening the portion with asmall curvature in each conductive thin wire and making the inclinationof the inclined portion of the cross sectional area be steep by thinningthe portion with a large curvature.

As a method for forming the conductive thin wire, for example, a methodfor forming the conductive thin wire with a desired wiring shape byetching a film to be the conductive thin wire is preferably used. In acase where the conductive thin wire is formed by etching, the conductivethin wire having various inclined portions can be formed by making adegree of erosion of a film by etching be relatively stronger to form asteep inclination of the inclined portion and making a degree of erosionof a film by etching be relatively weaker to form a gentle inclinationof the inclined portion. When the inclination of the inclined portion inthe thin portion of the conductive thin wire is made to be gentle byetching, erosion of the side of the film covered with a resist andetched is more proceeded than erosion of other portions, and all thefilm portion covered with the resist may be eroded before etching on theentire conductive thin wire is completed, and the conductive thin wiremay be disconnected.

Based on the analysis and findings, the inventors of the presentinvention have newly acquired knowledges such that prevention ofoccurrence of a beam of light and antiglare can be achieved at a highlevel by making the “inclination of the cross sectional area of thelarge curvature portion (first large curvature portion 231 b in FIG. 15to be described later) of the cross sectional area of the conductivethin wire (conductive main thin wire and conductive sub thin wire to bedescribed later) be larger than the inclination of the cross sectionalarea of the small curvature portion (first small curvature portion 231 ain FIG. 15 to be described later).

It is preferable to realize that “the conductive thin wire has differentinclination of the cross sectional area according to the curvature”across the entire heat-generating plate (conductive thin wire). However,such inclinations may be realized only in a part of the heat-generatingplate (conductive thin wire). For example, in a case where theheat-generating plate is applied to a vehicle window, the inclination ofthe cross sectional area of the conductive thin wire may be determinedaccording to the curvature in a range corresponding to a part of or allof a normal visual field of a vehicle occupant in the vehicle window. Inaddition, in only a part of the conductive thin wire, the inclination ofthe cross sectional area of the conductive thin wire may be determinedaccording to the curvature.

Hereinafter, a specific embodiment of the present invention based on theabove analysis and findings will be described.

FIG. 12 is a perspective view for schematically illustrating anautomobile (vehicle) 201 on which a battery (power supply) 207 ismounted.

In general, the automobile 201 has various windows such as a frontwindow, a rear window, side windows, and a sunroof window. Although atransparent heat-generating plate 210 according to the embodiment of thepresent invention can be applied to any window, an example in which thefront window 205 is formed of the transparent heat-generating plate 210will be described below.

FIG. 13 is a front view of the front window 205 formed of thetransparent heat-generating plate 210.

The heat-generating plate 210 in this example includes a firsttransparent plate 211, a second transparent plate 212, and a conductorsheet 220 arranged between the first transparent plate 211 and thesecond transparent plate 212. The conductor sheet 220 includes a pair ofbus bars 225 connected to a battery 207 via a wiring portion 215 and aheat-generating conductor (refer to reference numeral “230” in FIG. 14to be described later) arranged between the bus bars 225 and connectedto each of the pair of bus bars 225. When the battery 207 applies avoltage to the pair of bus bars 225, the heat-generating conductorconnected to the pair of bus bars 225 is energized and generates heat byresistance heating. Although the conductor sheet 220 including the busbars 225 and the heat-generating conductor is arranged in a sealed spacebetween the first transparent plate 211 and the second transparent plate212, the conductor sheet 220 is electrically connected to the battery207 provided outside via the wiring portions 215 extending from the busbars 225 to the outside of the first transparent plate 211 and thesecond transparent plate 212.

In the examples illustrated in FIGS. 12 and 13, the heat-generatingplate 210 (front window 205), the first transparent plate 211, and thesecond transparent plate 212 are curved. However, for easyunderstanding, in other figures, the heat-generating plate 210, thefirst transparent plate 211, and the second transparent plate 212 havingplate-like shape are illustrated.

FIG. 14 is a cross-sectional view of the heat-generating plate 210(front window 205) taking along a line XIV-XIV illustrated in FIG. 13.

The conductor sheet 220 includes a supporting base material 221 and aheat-generating conductor 230 arranged on and supported by thesupporting base material 221. A surface of the supporting base material221 on which the heat-generating conductor 230 is arranged is bonded tothe first transparent plate 211 via a first bonding layer 213, and asurface of the supporting base material 221 opposite to the surface onwhich the heat-generating conductor 230 is arranged is bonded to thesecond transparent plate 212 via a second bonding layer 214. Therefore,in the heat-generating plate 210 in this example, the first transparentplate 211 functions as a covering member for covering theheat-generating conductor 230, and the heat-generating conductor 230 isarranged between the supporting base material 221 and the firsttransparent plate 211.

Heat generated by the heat-generating conductor 230 is transmitted tothe first transparent plate 211 via the first bonding layer 213 andtransmitted to the second transparent plate 212 via the supporting basematerial 221 and the second bonding layer 214. As a result, the firsttransparent plate 211 and the second transparent plate 212 are heated,and frost, ice (snow and the like), and water attached to the firsttransparent plate 211 and the second transparent plate 212 are removed,and the fogging of the first transparent plate 211 and the secondtransparent plate 212 can be eliminated. By using the heat-generatingplate 210 as a defroster in this way, frost and ice formation and dewcondensation on the front window 205 (particularly, first transparentplate 211 and second transparent plate 212) are prevented so as to keepan excellent visibility of a vehicle occupant.

Transparence of the heat-generating plate 210 according to the presentembodiment is not particularly limited as long as the heat-generatingplate 210 is transparent enough so that the heat-generating plate 210can be viewed through from one side to the other side, and it ispreferable that the heat-generating plate 210 have a visible lighttransmittance of, for example, equal to or higher than 30%, and morepreferably, a visible light transmittance of equal to or higher than70%. Here, the visible light transmittance is specified as an averagevalue of transmittances in respective wavelengths when the transmittanceis measured by a spectrophotometer (for example, “UV-3100PC”manufactured by SHIMADZU CORPORATION, conforming to JISK0115) within ameasurement wavelength range of 380 nm to 780 nm.

In a case where the heat-generating plate 210 is used for the frontwindow 205 as in this example, it is especially required to secure aclear visibility by using the heat-generating plate 210. Therefore, itis preferable that the first transparent plate 211 and the secondtransparent plate 212 included in the heat-generating plate 210 used forthe front window 205 have a high visible light transmittance, forexample, a visible light transmittance of equal to or higher than 90%.As a material of each of the first transparent plate 211 and the secondtransparent plate 212, various members can be selected, and for example,a resin plate and a glass plate can be used. As a resin material formingthe first transparent plate 211 and the second transparent plate 212,acrylic resin polycarbonate such as polymethyl (meth) acrylate,polybutyl (meth) acrylate, methyl (meth) acrylate-butyl (meth) acrylatecopolymer, and methyl (meth) acrylate-styrene copolymer can beexemplified. The term of “(meth) acrylate” used here means acrylate ormethacrylate. The acrylic resin is suitable for the heat-generatingplate 210, and especially, for the heat-generating plate 210 used forthe front window 205 and the rear window in a point of high durability.In a part or all of the first transparent plate 211 and the secondtransparent plate 212, a visible light transmittance may be deteriorateddue to coloring or the like. For example, to prevent an increase in atemperature in a vehicle on a sunny summer day by shielding directsunlight or to make it difficult to visually recognize an interior ofthe vehicle from outside the vehicle, a part or all of the firsttransparent plate 211 and the second transparent plate 212 may have arelatively low visible light transmittance.

To secure high strength and excellent optical characteristics, it ispreferable that the first transparent plate 211 and the secondtransparent plate 212 have a thickness of equal to or more than 2 mm andequal to or less than 20 mm. In addition, the first transparent plate211 and the second transparent plate 212 may be formed of the samematerials, may have the same structures, and at least one of thematerials or structures of the first transparent plate 211 and thesecond transparent plate 212 may be different from each other.Furthermore, although the first transparent plate 211 and the secondtransparent plate 212 have substantially the same planar shape and size,the first transparent plate 211 and the second transparent plate 212 mayhave different planar shapes and sizes as necessary.

The “first bonding layer 213” for bonding the first transparent plate211 to the conductor sheet 220 (supporting base material 221) and the“second bonding layer 214” for bonding the second transparent plate 212and the conductor sheet 220 (supporting base material 221) are formed ofmaterials having various adhesiveness and viscosity and can be formed inlayers. From the viewpoint of securing a clear field of view, it ispreferable that the first bonding layer 213 and the second bonding layer214 be formed of a material with a high visible light transmittance, andtypically, formed of polyvinyl butyral (PVB). The thickness of each ofthe first bonding layer 213 and the second bonding layer 214 ispreferably equal to or more than 0.15 mm and equal to or less than 1 mm.In addition, the first bonding layer 213 and the second bonding layer214 may be formed of the same materials, may have the same structures,and at least one of the materials or structures of the first bondinglayer 213 and the second bonding layer 214 may be different from eachother.

The transparent heat-generating plate 210 is not limited to theillustrated example, and other function layer that is expected toperform a specific function may be provided, for example, in addition tothe above structure. Furthermore, each component of the heat-generatingplate 210 may perform two or more functions, and for example, a functionother than the above-described functions may be further added to atleast one component of the first transparent plate 211, the secondtransparent plate 212, the first bonding layer 213, the second bondinglayer 214, and the conductor sheet 220 (heat-generating conductor 230and supporting base material 221). For example, a member or structurethat provides at least one of an Anti-Reflection (AR) function, a HardCoating (HC) function having scratch resistance, an infrared rayshielding (reflection) function, an ultraviolet ray shielding(reflection) function, an antifouling function, and other functions maybe added to each component of the heat-generating plate 210.

<Conductor Sheet 220>

The conductor sheet 220 in this example includes the pair of bus bars225 and the heat-generating conductor 230 as described above, hassubstantially the same planar shape and size as the first transparentplate 211 and the second transparent plate 212, and is arranged over theentire first transparent plate 211 and the entire second transparentplate 212 (heat-generating plate 210). However, the planar shape and thesize of the conductor sheet 220 are not particularly limited, and theconductor sheet 220 may be smaller than the first transparent plate 211and the second transparent plate 212. For example, the conductor sheet220 may be provided on a part of the heat-generating plate 210 (firsttransparent plate 211 and second transparent plate 212) so that theconductor sheet 220 cover a specific area such as a front portion of adriver's seat.

A material of the supporting base material 221 of the conductor sheet220 is not particularly limited if the supporting base material 221 canappropriately support the heat-generating conductor 230, and thematerial preferably has a high visible light transmittance in theviewpoint of securing a clear field of view. Therefore, a transparentelectrically insulating film which can transmit light with wavelengthsin a visible light wavelength range (for example, 380 nm to 780 nm) canbe preferably used as the supporting base material 221. For example, thesupporting base material 221 can be formed of a polyester resin such aspolyethylene terephthalate, polyethylene naphthalate, polybutyleneterephthalate, and ethylene-terephthalate-isophthalate copolymer. Toappropriately support the heat-generating conductor 230 while keepingsufficient light transmittance, it is preferable that the supportingbase material 221 have the thickness of equal to or more than 0.03 mmand equal to or less than 0.15 mm.

On the other hand, a material of the heat-generating conductor 230 isnot particularly limited as long as the material can be heated by beingenergized. For example, the heat-generating conductor 230 can be formedof gold, silver, copper, platinum, aluminum, chromium, molybdenum,nickel, titanium, palladium, indium, tungsten, or an alloy thereof. Theheat-generating conductor 230 may be formed of an opaque metal material.However, in a case where the heat-generating conductor 230 is formed ofan opaque material or a material with low transparence, it is preferableto sufficiently thin the heat-generating conductor 230 so as not toexcessively shield a field of view of a user.

Therefore, it is preferable that a proportion (that is, uncoating ratio)of a region that is not covered with the heat-generating conductor 230of a planar area of the supporting base material 221 be set to high, forexample, equal to or higher than 70% and equal to or lower than 98%.Furthermore, it is preferable that a line width of the conductive thinwire (conductive main thin wire 231 or conductive sub thin wire 232 tobe described later) included in the heat-generating conductor 230 beabout equal to or more than 2 μm and equal to or less than 20 μm.Specifically, regarding the sizes of the conductive thin wire, it ispreferable that the width W in a direction along the plate surface ofthe transparent heat-generating plate 210 be about equal to or more than2 μm and equal to or less than 20 μm, and it is preferable that theheight (thickness) H in a normal direction of the plate surface of thetransparent heat-generating plate 210 be equal to or more than 1 μm andequal to or less than 20 μm. If the heat-generating conductor 230(conductive thin wire) has the width W and the height H as describedabove, the heat-generating conductor 230 is sufficiently thin and can bevisually inconspicuous. By providing the heat-generating conductor 230based on the uncoating ratio and the line width, the entire region wherethe heat-generating conductor 230 is provided has high transparence, andthe heat-generating conductor 230 does not excessively impair visuallytransmitting performance of the transparent heat-generating plate 210.

As described above, the heat-generating conductor 230 is formed on thesupporting base material 221 so as to increase the uncoating ratio, andthe first bonding layer 213 has contact with the heat-generatingconductor 230 and has contact with a portion (non-coated portion) of thesupporting base material 221 that is not covered with theheat-generating conductor 230. Therefore, in the heat-generating plate210 in this example, the heat-generating conductor 230 is embedded inthe first bonding layer 213.

Regarding the heat-generating conductor 230, a surface portion may havea dark color layer (refer to “first dark color layer 237” and “seconddark color layer 238” illustrated in FIG. 25 and the like to bedescribed later), and at least a part of an energized portion at thecenter of the heat-generating conductor 230 (refer to “conductive layer236” illustrated in FIG. 25 and the like) may be covered with the darkcolor layer. Depending on the material, the heat-generating conductor230 may have a relatively high light reflectance, and there is a casewhere light reflected by the heat-generating conductor 230 is visuallyconspicuous. The light reflected by the heat-generating conductor 230interferes the field of view of a vehicle occupant in a vehicle anddeteriorates design by allowing the visual recognition of theheat-generating conductor 230 from the outside of the vehicle.Therefore, by forming a dark color layer such as black layer havinglower visual light reflectance than that of the energized portion at thecenter of the heat-generating conductor 230 on the surface of theheat-generating conductor 230, reflection of light by theheat-generating conductor 230 can be prevented, and the deterioration indesign can be prevented while securing an excellent field of view of avehicle occupant.

Next, a wiring pattern of the heat-generating conductor 230 according tothe present embodiment will be described.

FIG. 15 is an enlarged plan view illustrating an exemplary wiringpattern of the heat-generating conductor 230. In FIG. 15, forconvenience of explanation, of the heat-generating plate 210, only theheat-generating conductor 230 and the supporting base material 221 areillustrated.

The heat-generating conductor 230 according to the present embodimentincludes a plurality of conductive main thin wires 231 and conductivesub thin wires 232 for coupling the conductive main thin wires 231arranged adjacent to each other. Each conductive main thin wire 231extends in a direction from one bus bar 225 toward the other bus bar 225(refer to Y direction in FIG. 15) between the pair of bus bars 225(refer to FIG. 13) and are connected to the bus bars 225. Eachconductive main thin wire 231 is curved in an irregular wavy shape andarranged on the supporting base material 221, and the conductive mainthin wire 231 has a plurality of curved portions having differentcurvatures (that is, curved degree) from each other. In addition, theconductive main thin wires 231 have different wave shapes from eachother.

The conductive sub thin wire 232 is provided on at least a part of theplurality of conductive main thin wires 231 and is discretely arranged.That is, the plurality of conductive sub thin wires 232 is arranged inthe present embodiment, and the conductive sub thin wires 232 arearranged at positions different from each other along the direction fromone of the bus bars 225 to the other bus bar 225 (refer to Y directionin FIG. 15). Each conductive sub thin wire 232 has an irregular wavyshape including a plurality of curved portions having differentcurvatures (that is, curved degree) from each other. In addition, theconductive sub thin wires 232 have different wave shapes from eachother. The conductive sub thin wire 232 and the conductive main thinwire 231 have the same composition and are continuously and integrallyformed.

As described above, each of the conductive main thin wires 231 and theconductive sub thin wires 232 included in the heat-generating conductor230 has curved portions with various curvatures. In particular, theconductive main thin wire 231 according to the present embodimentincludes a “portion with a relatively small curvature (first smallcurvature portion, refer to reference numeral “231 a” in FIG. 15)” and a“portion with a relatively large curvature (first large curvatureportion, refer to reference numeral “231 b” in FIG. 15)” of which crosssectional areas have different inclinations. That is, the inclination ofthe cross section of the first large curvature portion with a relativelylarge curvature of the cross section of the conductive main thin wire231 is larger than that of the first small curvature portion with arelatively small curvature.

FIG. 16A is an enlarged view of a portion (first small curvatureportion) indicated by the reference numeral “231 a” in FIG. 15, and FIG.16B is an enlarged view of a portion (first large curvature portion)indicated by the reference numeral “231 b” in FIG. 15. FIG. 17A is across-sectional view taken along a line XVIIA-XVIIA in FIG. 16A, andFIG. 17B is a cross-sectional view taken along a line XVIIB-XVIIB inFIG. 16B.

A cross section of the heat-generating conductor 230 (conductive mainthin wire 231 and conductive sub thin wire 232) according to the presentembodiment is divided by a lower bottom S3 having contact with thesupporting base material 221, an upper bottom S1 arranged at a positionfacing to the lower bottom S3, a first inclined portion S2 extendingbetween one end E2 of the lower bottom S3 and one end E1 of the upperbottom S1, and a second inclined portion S4 extending between the otherend E4 of the lower bottom S3 and the other end E3 of the upper bottomS1 (refer to FIGS. 17A and 17B). In addition, the cross sectional areaof the heat-generating conductor 230 (conductive main thin wire 231 andconductive sub thin wire 232) according to the present embodiment issubstantially symmetrically formed with an axis passing through thecenter of the upper bottom S1 and the center of the lower bottom S3.

An inclination of the cross sectional area of the heat-generatingconductor 230 (conductive main thin wire 231 and conductive sub thinwire 232) is expressed by each of an inclination of a straight linepassing through the one end E2 of the lower bottom S3 and the one end E1of the upper bottom S1 and an inclination of a straight line passingthrough the other end E4 of the lower bottom S3 and the other end E3 ofthe upper bottom S1.

As described above, in the conductive main thin wire 231 according tothe present embodiment, the inclination of the cross sectional area of alarge curvature portion (first large curvature portion) 31 b with arelatively large curvature is larger than the inclination of the crosssectional area of a small curvature portion (first small curvatureportion) 31 a with a relatively small curvature. Therefore, an“inclination angle θ1” formed by each of a “straight line T1 passingthrough the one end E2 of the lower bottom S3 and the one end E1 of theupper bottom S1” and a “straight line T1 passing through the other endE4 of the lower bottom S3 and the other end E3 of the upper bottom S1”of the small curvature portion 231 a illustrated in FIG. 17A and thelower bottom S3 and an “inclination angle θ2” formed by a “straight lineT2 passing through the one end E2 of the lower bottom S3 and the one endE1 of the upper bottom S1” and a “straight line T2 passing through theother end E4 of the lower bottom S3 and the other end E3 of the upperbottom S1” of the large curvature portion 231 b illustrated in FIG. 17Band the lower bottom S3 satisfy the following relational expression 1.

θ1<θ2  <Relational Expression 1>

In addition, the heights of the cross sectional areas of theheat-generating conductors 230 (conductive main thin wire 231 andconductive sub thin wire 232) are almost the same. That is, an intervalH1 between the upper bottom S1 and the lower bottom S3 of the crosssectional area of the small curvature portion 231 a illustrated in FIG.17A is equal to an interval H2 between the upper bottom S1 and the lowerbottom S3 of the cross sectional area of the large curvature portion 231b illustrated in FIG. 17B, and the following relational expression 2 issatisfied.

H1=H2  <Relational Expression 2>

A projection size P1 (refer to FIG. 17A) of the cross sectional area ofthe small curvature portion 231 a on the supporting base material 221 islarger than a projection size P2 (refer to FIG. 17B) of the crosssectional area of the large curvature portion 231 b on the supportingbase material 221, and the following relational expression 3 issatisfied. That is, along the direction along a supporting surface ofthe supporting base material 221 (refer to X direction in FIGS. 17A and17B), the “length of the entire cross sectional area (particularly,lower bottom S3 in the present embodiment) of the small curvatureportion 231 a” is longer than the “length of the entire cross sectionalarea (particularly, lower bottom S3 in the present embodiment) of thelarge curvature portion 231 b”.

P1>P2  <Relational Expression 3>

Furthermore, the sum of a “projection size P3 a of the first inclinedportion S2” and a “projection size P3 b of the second inclined portionS4” of the cross sectional area of the small curvature portion 231 a onthe supporting base material 221 is larger than the sum of a “projectionsize P4 a of the first inclined portion S2” and a “projection size P4 bof the second inclined portion S4” of the cross sectional area of thelarge curvature portion 231 b on the supporting base material 221, andthe following relational expression 4 is satisfied. That is, along thedirection along the supporting surface of the supporting base material221, the “sum of the lengths of the first inclined portion S2 and thesecond inclined portion S4 of the cross sectional area of the smallcurvature portion 231 a” is larger than the “sum of the lengths of thefirst inclined portion S2 and the second inclined portion S4 of thecross sectional area of the large curvature portion 231 b”.

(P3a+P3b)>(P4a+P4b)  <Relational Expression 4>

A projection size W1 of the upper bottom S1 of the cross sectional areaof the small curvature portion 231 a on the supporting base material 221is larger than a projection size W2 of the upper bottom S1 of the crosssectional area of the large curvature portion 231 b on the supportingbase material 221.

An area of the cross sectional area of the small curvature portion 231 ais larger than an area of the cross sectional area of the largecurvature portion 231 b.

As described above, according to the present embodiment, the shape andthe size of the cross sectional area of each conductive thin wire(conductive main thin wire 231) is determined according to the curvatureof the wire of the heat-generating conductor 230 (conductive thin wire),and generation of a beam of light and generation of glare can beprevented at a high level. That is, by forming the conductive main thinwire 231 with “a plurality of conductive thin wires irregularly arrangedwith various curvatures”, generation of a beam of light that can bevisually recognized can be effectively prevented. Furthermore, byinclining the cross sectional area of the conductive main thin wire 231with various angles (refer to “θ1” in FIG. 17A and “θ2” in FIG. 17B),glare such as dazzle and blur can be effectively prevented. Then, “bysetting the inclination of the cross sectional area of the largecurvature portion (large curvature portion 231 b) of the cross sectionalarea of the conductive main thin wire 231 to be larger than theinclination of the cross sectional area of the small curvature portion(small curvature portion 231 a)”, “the prevention of generation of abeam of light” and “antiglare” can be achieved at a high level whileavoiding disconnection of the conductive main thin wire 231.

The configuration of the conductive main thin wire 231 is effective forthe conductive sub thin wire 232 (refer to FIG. 15), and it ispreferable for the cross sectional area of the conductive sub thin wire232 to similarly satisfy the relationship regarding the cross sectionalarea of the conductive main thin wire 231. Therefore, “the conductivesub thin wire 232 includes a plurality of conductive thin wiresirregularly arranged as having various curvatures”, “the conductive subthin wire 232 includes a curved portion with a relatively largecurvature (second large curvature portion) and a curved portion with arelatively small curvature (second small curvature portion)”, “the crosssectional areas of the conductive sub thin wire 232 have inclinationswith various angles”, and “the inclination of the cross sectional areaof the large curvature portion (second large curvature portion) of thecross sectional area of the conductive sub thin wire 232 is set to belarger than the inclination of the cross sectional area of the smallcurvature portion (second small curvature portion) so that “theprevention of generation of a beam of light” and “antiglare” can beachieved at a high level while avoiding disconnection of the conductivesub thin wire 232.

In addition, the structure of the heat-generating plate 210 is notlimited to that illustrated in FIG. 14, and other layers may be added,and elements other than the heat-generating conductor 230 may beomitted. For example, as illustrated in FIG. 18, the first transparentplate 211 is directly laminated on the surface of the supporting basematerial 221 on which the heat-generating conductor 230 is provided soas to cover the heat-generating conductor 230, and the first transparentplate 211, the heat-generating conductor 230, and the supporting basematerial 221 may form the heat-generating plate 210. In addition, otherfunction layer may be appropriately added to the heat-generatingconductor 230 illustrated in FIG. 18.

<Manufacturing Method for Heat-Generating Plate 210>

Next, a manufacturing method for the heat-generating plate 210 will bedescribed. The manufacturing method for the heat-generating plate 210 isnot particularly limited. However, as an example, a method of forming aconductive thin wire (conductive main thin wire 231 and conductive subthin wire 232) including a conductive layer and a dark color layer onthe supporting base material 221 will be described below. In thefollowing description, an example of a manufacturing method for theheat-generating plate 210 illustrated in FIG. 18 will be described.However, the heat-generating plate 210 having other structure (refer toFIG. 14) can be manufactured by appropriately applying the followingmanufacturing method.

FIGS. 19 to 25 are cross-sectional views for explaining an example ofthe manufacturing method for the heat-generating plate 210, andprocesses for manufacturing the heat-generating plate 210 will besequentially described.

First, as illustrated in FIG. 19, a dark color film 237 a to be a firstdark color layer of the heat-generating conductor 230 (conductive mainthin wire 231 and conductive sub thin wire 232) is laminated on a copperfoil film 236 a which is a member to be a conductive layer of theheat-generating conductor 230 (conductive main thin wire 231 andconductive sub thin wire 232). A method for forming the copper foil film236 a is not particularly limited, and the copper foil film 236 a can beformed by a known method. For example, the copper foil film 236 a may beformed by one of or a combination of two or more of a plating methodincluding electroplating and electroless plating, a sputtering method, aCVD method, a PVD method, and an ion plating method. A method forforming the dark color film 237 a is not particularly limited, and thedark color film 237 a can be formed by a known method. For example, thedark color film 237 a can be formed on the copper foil film 236 a by oneof or a combination of two or more of a plating method includingelectroplating and electroless plating, a sputtering method, a CVDmethod, a PVD method, and an ion plating method. The dark color film 237a can be formed of various known materials and may be formed of, forexample, copper nitride, copper oxide, or nickel nitride.

Next, as illustrated in FIG. 20, a transparent supporting base material221 is laminated on a surface opposite to the surface of the dark colorfilm 237 a on which the copper foil film 236 a is laminated. Thesupporting base material 221 and the dark color film 237 a may be surelybonded to each other by providing a bonding layer including an adhesiveagent and an adhesive between the supporting base material 221 and thedark color film 237 a. The supporting base material 221 may be formed ofany member as long as the supporting base material 221 can appropriatelysupport the heat-generating conductor 230, and for example, a biaxiallystretched polyester resin such as polyethylene terephthalate andpolyethylene naphthalate can be exemplified as a material of thesupporting base material 221. However, in consideration of retention ofthe heat-generating conductor 230 and the like, it is preferable thatthe thickness of the supporting base material 221 be equal to or morethan 30 μm and equal to or less than 150 μm.

Next, as illustrated in FIG. 21, a resist pattern 239 is provided on asurface of the copper foil film 236 a opposite to the surface on whichthe dark color film 237 a is laminated. The resist pattern 239 isarranged on the copper foil film 236 a so as to finally have a shapecorresponding to a wiring pattern (wiring shape) of the heat-generatingconductor 230 to be formed on the supporting base material 221. That is,the resist pattern 239 is provided only on a portion of the copper foilfilm 236 a that finally forms the heat-generating conductor 230(conductive main thin wire 231 and conductive sub thin wire 232). Theresist pattern 239 can be formed by patterning using a knownphotolithography technique. For example, in a case of using proximityexposure with a photomask, when a negative type photoresist is used, adesired resist pattern 239 can be formed on the copper foil film 236 aby forming a shielding pattern on the photomask and performingpatterning.

Next, the resist pattern 239 is used as a mask, and the copper foil film236 a and the dark color film 237 a are etched. By this etching, thecopper foil film 236 a and the dark color film 237 a are patterned tohave planar shapes substantially the same as the resist pattern 239. Asa result of the patterning, as illustrated in FIG. 22, the conductivelayer 236 to be a part of the conductive thin wire (conductive main thinwire 231 and conductive sub thin wire 232) is formed from the copperfoil film 236 a, and a first dark color layer 237 to be a part of theconductive thin wire (conductive main thin wire 231 and conductive subthin wire 232) is formed from the dark color film 237 a.

An etching method is not particularly limited, and a known method can beemployed. For example, the copper foil film 236 a and the dark colorfilm 237 a can be etched by wet etching using an etchant such as anaqueous ferric chloride solution or dry etching such as plasma etching.

Next, as illustrated in FIG. 23, the resist pattern 239 is removed by anarbitrary method. Accordingly, the heat-generating conductor 230(conductive layer 236 and first dark color layer 237) wired on thesupporting base material 221 in a predetermined pattern is obtained.

Next, as illustrated in FIG. 24, a second dark color layer 238 is formedon a surface 235 a of the conductive layer 236 opposite to the surface235 b on which the first dark color layer 237 is provided and on sidesurfaces 35 c and 35 d of the conductive layer 236. A method of formingthe second dark color layer 238 is not particularly limited. Forexample, the dark color layer 238 can be formed from a part of thematerial forming the conductive layer 236 by performing darkeningprocessing (blackening processing) on a part of the conductive layer236. Since the conductive layer 236 according to the present embodimentis formed of copper (copper foil film 236 a), the second dark colorlayer 238 formed of, for example, copper oxide or copper sulfide can beformed as a surface layer of the conductive layer 236.

Alternatively, a second dark color layer 238 such as a coating film of adark color material, a plating layer of nickel or chromium, or asputtered layer of copper oxide (CuO) or copper nitride may beadditionally provided on the surface of the conductive layer 236. In acase where the second dark color layer 238 is additionally provided, thesecond dark color layer 238 may be provided on the conductive layer 236after at least a part of the surfaces (surface 235 a and side surfaces235 c and 235 d) of the conductive layer 236 is roughened.

Through the series of processes (refer to FIGS. 19 to 24), theheat-generating conductor 230 (conductive main thin wire 231 andconductive sub thin wire 232) coated with the conductive layer 236 bythe first dark color layer 237 and the second dark color layer 238 isformed on the supporting base material 221, and the conductor sheet 220is produced. In this way, the heat-generating conductor 230 is formed onthe supporting base material 221 separated from the first transparentplate 211 (refer to FIG. 18), and it is preferable that the supportingbase material 221 have an appropriate thickness as a supporting memberat the time when the heat-generating conductor 230 is formed, and thethickness to apply rigidity to the heat-generating plate 210 is notrequired for the supporting base material 221. Therefore, according tothe series of manufacturing methods illustrated in FIGS. 19 to 24, alarge number of heat-generating conductors 230 used for the plurality ofheat-generating plates 210 can be sequentially formed on a longsupporting base material 221, and the heat-generating conductor 230 canbe manufactured at a very low cost than a conventional method forforming a heat-generating conductor for each heat-generating plate 210.In addition, according to the manufacturing method described above,since a part of the pair of bus bars 225 and the wiring portion 215illustrated in FIG. 13 can be formed with the heat-generating conductor230 by using the same material as the heat-generating conductor 230, theconductor sheet 220 and the heat-generating plate 210 can beinexpensively manufactured. Furthermore, according to the manufacturingmethod described above, a part of the pair of bus bars 225 and thewiring portion 215 can be integrally form with the heat-generatingconductor 230 by using the same material as the heat-generatingconductor 230. In this case, electrical connection from theheat-generating conductor 230 to the wiring portion 215 via the bus bars225 can be more stably secured.

Next, the first transparent plate 211 is laminated on the surface of thesupporting base material 221 on which the heat-generating conductor 230(conductive layer 236, first dark color layer 237, and second dark colorlayer 238) is provided. FIG. 25 illustrates an example in which thefirst transparent plate 211 is formed by injection molding and bonded tothe supporting base material 221. In the example illustrated in FIG. 25,the conductor sheet 220 is arranged in a cavity 241 a of a mold 241 forinjection molding. The conductor sheet 220 is arranged in the cavity 241a so that the surface of the supporting base material 221 on which theheat-generating conductor 230 is arranged faces inward of the cavity 241a and a resin supplied from a resin supply port 42 of the mold 241 tothe cavity 241 a is laminated on the “surface of the supporting basematerial 221 on which the heat-generating conductor 230 is arranged”.Then, a resin such as acrylic which is heated and has fluidity isinjected from the resin supply port 42 of the mold 241 to the cavity 241a and laminated on the supporting base material 221 and theheat-generating conductor 230 (conductive layer 236, first dark colorlayer 237, and second dark color layer 238). The resin injected into thecavity 241 a is cooled in the cavity 241 a and solidified on thesupporting base material 221 and the heat-generating conductor 230, andfinally forms the first transparent plate 211 to be bonded to thesupporting base material 221 and the heat-generating conductor 230.According to the injection molding described above, even when the firsttransparent plate 211 (heat-generating plate 210) has a plate-like shapeor curved plate-like shape, the first transparent plate 211(heat-generating plate 210) can be easily and inexpensively formed onthe conductor sheet 220 (supporting base material 221 andheat-generating conductor 230).

A primer layer to secure adhesiveness may be provided in advance on asurface of the conductor sheet 220 (supporting base material 221) onwhich the heat-generating conductor 230 is formed. In this case, theprimer layer can improve adhesion between the conductor sheet 220(supporting base material 221) and the first transparent plate 211.

According to the manufacturing method for the heat-generating plate 210illustrated in FIGS. 19 to 25, the heat-generating conductor 230 can bearranged between the first transparent plate 211 and the supporting basematerial 221 relatively easily and reliably. In particular, by using thefirst transparent plate 211 as a covering member of the heat-generatingconductor 230, it is not necessary to use glass having a large weightdensity as a supporting base material of the heat-generating conductor230, and the weight of the heat-generating plate 210 can be largelyreduced. In addition, since the heat-generating conductor 230 is formedon the supporting base material 221 that functions as a supportingmember, the conductor sheet 220 that can be easily handled can beprovided. Therefore, according to the series of manufacturing methods,based on a photolithography technique, the conductor sheet 220 can beeasily and quickly formed typically in a role-to-role manner. In thisway, according to the manufacturing method for the heat-generating plate210 illustrated in FIGS. 19 to 25, the plurality of heat-generatingconductors 230 can be continuously, efficiently and inexpensivelymanufactured, and the heat-generating plate 210 of which the weight isfinally reduced can be inexpensively and stably manufactured.

Modification

The present invention is not limited to the embodiments, and variouschanges may be made to the embodiments.

For example, in the above manufacturing method, as illustrated in FIG.25, although the heat-generating plate 210 is formed in which thesupporting base material 221, the heat-generating conductor 230, and thefirst transparent plate 211 are sequentially laminated, other layers maybe further laminated. For example, on at least one of “the surface ofthe first transparent plate 211 opposite to the surface bonded to thesupporting base material 221” and “the surface of the supporting basematerial 221 (conductor sheet 220) opposite to the surface to be bondedto the first transparent plate 211”, the other coating layer may belaminated.

FIG. 26 is a cross-sectional view illustrating another modification ofthe heat-generating plate 210. In addition of the supporting basematerial 221, the heat-generating conductor 230, and the firsttransparent plate 211 (refer to FIG. 25), the heat-generating plate 210of this example further includes a transparent coating layer 245 forcoating the first transparent plate 211 from a side opposite to theconductor sheet 220 and a transparent coating layer 246 for covering theconductor sheet 220 from a side opposite to the first transparent plate211. The coating layers 245 and 246 forming a surface layer (outermostsurface) of the heat-generating plate 210 function as a hard coatinglayer having scratch resistance and protect the first transparent plate211 and the conductor sheet 220 to improve durability of theheat-generating plate 210. These coating layers 245 and 246 can beformed by using, for example, a known acrylic ultraviolet curable resin.That is, on each of the first transparent plate 211 and the conductorsheet 220 (supporting base material 221), a composition including amonomer of an acrylic ultraviolet curable resin, a prepolymer, or bothof them, and a photopolymerization initiator is coated in a film-likeshape. Then, by irradiating the coated film with ultraviolet rays andcuring the coated film by crosslinking reaction or polymerization, acured resin is obtained. The cured resin layer obtained in this way canbe used as the coating layers 245 and 246 that function as hard coatinglayers.

In the above embodiment (for example, refer to FIG. 25), although thefirst transparent plate 211 is laminated on the conductor sheet 220(supporting base material 221 and heat-generating conductor 230) so asto face to the surface of the conductor sheet 220 on which theheat-generating conductor 230 is provided, the arranged position of thefirst transparent plate 211 is not limited to this.

FIG. 27 is a cross-sectional view illustrating still anothermodification of the heat-generating plate 210. In the heat-generatingplate 210 in this example, the first transparent plate 211 is laminatedon the conductor sheet 220 (supporting base material 221) so as to faceto a surface opposite to the surface of the conductor sheet 220(supporting base material 221) on which the heat-generating conductor230 is provided. In this example, since the heat-generating conductor230 is exposed outside without being coated with the first transparentplate 211, there is a possibility that an external force such as animpact acts on and disconnects the heat-generating conductor 230 and theheat-generating conductor 230 rusts due to moisture in the air or thelike. Therefore, in a case where the heat-generating conductor 230 isnot coated with the first transparent plate 211, it is preferable thatthe heat-generating conductor 230 is coated with another coating layerto prevent exposure of the heat-generating conductor 230 to the outside.

FIG. 28 is a cross-sectional view illustrating yet another modificationof the heat-generating plate 210. The heat-generating plate 210 of thisexample can be obtained by applying the coating layers 245 and 246illustrated in FIG. 26 to the heat-generating plate 210 illustrated inFIG. 27. That is, the coating layer 245 is provided on the surface ofthe conductor sheet 220 (supporting base material 221) on which theheat-generating conductor 230 is provided, and the heat-generatingconductor 230 is coated with the coating layer 245. With the coatinglayer 245, the heat-generating conductor 230 is separated from outsideand is protected, disconnection and rust of the heat-generatingconductor 230 can be prevented. Furthermore, the coating layer 246 isprovided on the surface of the first transparent plate 211 opposite tothe surface on which the supporting base material 221 is provided, andthe first transparent plate 211 is coated with the coating layer 246. Asa result, the first transparent plate 211 is separated from outside andis protected, and durability of the heat-generating plate 210 can beimproved.

In addition, at least one of layers of the heat-generating plate 210 mayinclude ultraviolet ray absorber dispersed therein. In this case, sincethe ultraviolet ray absorber absorbs ultraviolet rays and an amount ofultraviolet rays, entering from outside, on the inner side of the layerincluding the ultraviolet ray absorber is reduced, deterioration such asyellowing caused by ultraviolet rays caused in a member on the innerside of the layer including the ultraviolet ray absorber can beeffectively prevented. That is, by including the ultraviolet rayabsorber in the heat-generating plate 210, the light resistance propertyof the heat-generating plate 210 can be improved. As an example of theultraviolet ray absorber, benzotriazole-based compounds andbenzophenone-based compounds can be exemplified. It is preferable that amass ratio of the ultraviolet ray absorber in the layer including theultraviolet ray absorber be 0.5 to 5.0 mass %.

In a case where a coating layer is provided on the heat-generating plate210, a moisture permeability of the coating layer may be lower than thatof the supporting base material 221. By a coating layer with a lowmoisture permeability, it is possible to effectively prevent water vaporfrom reaching the heat-generating conductor 230 (conductive main thinwire 231 and conductive sub thin wire 232), and deterioration in theheat-generating conductor 230 (conductive main thin wire 231 andconductive sub thin wire 232) due to rust can be prevented. The moisturepermeability can be measured by a method specified in JISZ0208.

Furthermore, the heat-generating plate 210 may have a curved shape, aplate-like shape, and other shape according to the application.

Furthermore, in the above embodiment, an example in which an acrylicresin is used as a material of the first transparent plate 211 has beendescribed. However, the present invention is not limited to thisexample. For example, a polyolefin resin, a polycarbonate resin, a vinylchloride resin, or the like may be used as the material of the firsttransparent plate 211.

Furthermore, in the above embodiment, regarding a method for laminatingthe first transparent plate 211 and the conductor sheet 220, an exampleis illustrated in which the first transparent plate 211 and theconductor sheet 220 are laminated and integrated (refer to FIG. 25) byinjection-molding and filling a melt of the resin forming the firsttransparent plate 211 into the cavity, after arranging the conductorsheet 220 in the mold cavity for molding the first transparent plate 211in advance. However, the present invention is not limited to this. Forexample, the first transparent plate 211 and the conductor sheet 220 maybe laminated and integrated by preparing the previously molded firsttransparent plate 211 and bonding the conductor sheet 220 on one of thesurfaces of the first transparent plate 211 via an adhesive layer. As aspecific example, the heat-generating plate 210 illustrated in FIG. 24can be produced by heating and pressurizing the first transparent plate211 and the second transparent plate 212 to bond these plates to theconductor sheet 220 via the first bonding layer 213 and the secondbonding layer 214 formed of polyvinyl butyral (PVB).

The heat-generating plate 210 may be used not only for a window of theautomobile 201 but also for windows and doors of vehicles other than theautomobile 201 (for example, train, aircraft, ship and spacecraft).

In addition, the heat-generating plate 210 can be applied to anythingother than the vehicles and can be appropriately used for a “place fordividing a space (for example, indoor and outdoor)” such as windows forbuildings such as shops and houses.

Furthermore, the embodiments and the modifications may be appropriatelycombined.

Fourth Embodiment

In the present specification, terms of “plate”, “sheet”, and “film” arenot distinguished from each other only based on a difference in thename. For example, “a sheet with a conductor” is a concept including amember which can be called as plate and film. Therefore, the “sheet witha conductor” is not distinguished from members called as “a plate(substrate) with a conductor” and “a film with a conductor” only basedon only the difference in the name. The “conductive pattern sheet” isnot distinguished from a member called as a “conductive pattern plate(substrate)” and a “conductive pattern film” only based on thedifference in the name.

In addition, in the present specification, a “sheet surface (platesurface and film surface)” indicates a surface that coincides with aplanar direction of a sheet-like member to be a target (plate-likemember and film-like member) in a case where an entire sheet-like memberto be a target (plate-like and film-like) is viewed from a largeperspective. Furthermore, a normal direction relative to a sheet-likemember (plate-like and film-like) indicates a normal direction along asheet surface (film surface and plate surface) of the sheet-like(plate-like and film-like) member.

In addition, terms used herein for specifying shapes and geometricalconditions and degrees thereof, for example, terms of “parallel”,“perpendicular”, “same” and values of lengths and angles are not limitedto strict meanings and are interpreted as a including a range of termsthat can be expected to have a similar function.

FIGS. 29 to 43 are views for explaining one embodiment of the presentinvention. FIG. 29 is a view schematically illustrating an automobileincluding a heat-generating plate, FIG. 30 is a view of theheat-generating plate viewed from the normal direction of the platesurface, and FIG. 31 is a cross-sectional view of the heat-generatingplate in FIG. 30.

As illustrated in FIG. 29, an automobile 301 as an example of a vehicleincludes a window glass such as a front window, a rear window, and aside window. Here, an example in which a front window 305 is configuredby a heat-generating plate 310 will be described. In addition, theautomobile 301 includes a power supply 307 such as a battery.

As illustrated in FIGS. 30 and 31, the heat-generating plate 310according to the present embodiment includes a pair of glasses 311 and312, a sheet with a conductor 320 arranged between the pair of glasses311 and 312, and a pair of bonding layers 313 and 314 for bonding therespective glasses 311 and 312 to the sheet with a conductor 320. In theexamples illustrated in FIGS. 29 and 30, the heat-generating plate 310and the glasses 311 and 312 are curved. However, in other drawings, foreasy understanding, the heat-generating plate 310 and the glasses 311and 312 having plate-like shapes are illustrated.

The sheet with a conductor 320 includes a base film 321, a bus bar 325,and a heat-generating conductor 330 provided on a surface of the basefilm 321 facing to the glass 311 and including a conductive thin wire331.

As illustrated in FIG. 30, the heat-generating plate 310 includes awiring portion 315 for energizing the heat-generating conductor 330 ofthe sheet with a conductor 320 via the bus bar 325. In the illustratedexample, the power supply 307 such as a battery supplies power to theheat-generating conductor 330 via the wiring portion 315 and the bus bar325, and the conductive thin wire 331 of the heat-generating conductor330 are heated by resistance heating. Heat generated by theheat-generating conductor 330 is transmitted to the glasses 311 and 312and heat the glasses 311 and 312. As a result, fogging due to dewcondensation attached on the glasses 311 and 312 can be removed. In acase where snow or ice is attached on the glasses 311 and 312, snow andice can be melted. Therefore, a passenger's visibility is preferablysecured.

Each component of the heat-generating plate 310 will be described below.

First, the glasses 311 and 312 will be described. When the glasses 311and 312 are used for a front window of an automobile as in the exampleillustrated in FIG. 29, it is preferable to use a glass with a highvisible light transmittance so as not to interfere the field of view ofa passenger. As a material of the glasses 311 and 312, soda-lime glassand blue plate glass can be used. It is preferable that a transmittanceof the glasses 311 and 312 in a visible light region be equal to orhigher than 90%. Here, the visible light transmittance of the glasses311 and 312 are specified as an average value of transmittances inrespective wavelength when the transmittance is measured by aspectrophotometer (“UV-3100PC” manufactured by SHIMADZU CORPORATION,conforming to JIS K 0115) within a measurement wavelength range of 380nm to 780 nm. The visible light transmittance may be lowered by coloringa part of or all of the glasses 311 and 312. In this case, directsunlight can be shielded, and it is possible to make it difficult tovisually recognize an interior of the vehicle from the outside of thevehicle.

Furthermore, it is preferable that the glasses 311 and 312 have athickness of equal to or more than 1 mm and equal to or less than 5 mm.With such a thickness, the glasses 311 and 312 having excellent strengthand optical characteristics can be obtained. The pair of glasses 311 and312 may be formed of the same material and with the same structure, orat least one of the material and the structure may be different.

Next, the bonding layers 313 and 314 will be described. The firstbonding layer 313 is arranged between the first glass 311 and the sheetwith a conductor 320 and bonds the glass 311 to the sheet with aconductor 320. The second bonding layer 314 is arranged between thesecond glass 312 and the sheet with a conductor 320 and bonds the glass312 to the sheet with a conductor 320.

As such bonding layers 313 and 314, a layer formed of a material havingvarious adhesiveness and viscosity can be used. Furthermore, it ispreferable to use a material having a high visible light transmittancefor the bonding layers 313 and 314. As a typical bonding layer, a layerformed of polyvinyl butyral (PVB) can be exemplified. It is preferablethat the thickness of each of the bonding layers 313 and 314 be equal toor more than 0.15 mm and equal to or less than 1 mm. The pair of bondinglayers 313 and 314 may be formed of the same material and with the samestructure, or at least one of the material and the structure may bedifferent.

The heat-generating plate 310 is not limited to the illustrated example,and other function layer that is expected to perform a specific functionmay be provided. Furthermore, one function layer may perform two or morefunctions, and for example, some function may be added to at least oneof the glasses 311 and 312 of the heat-generating plate 310, the bondinglayers 313 and 314, and the base film 321 of the sheet with a conductor320 to be described later. As an example of the function that can beapplied to the heat-generating plate 310, an anti-reflection (AR)function, a hard coating (HC) function having scratch resistance, aninfrared ray shielding (reflection) function, an ultraviolet rayshielding (reflection) function, and an antifouling function can beexemplified.

Next, the sheet with a conductor 320 will be described. The sheet with aconductor 320 includes a base film 321, a bus bar 325, and aheat-generating conductor 330 provided on a surface of the base film 321facing to the glass 311 and including a conductive thin wire 331. Thesheet with a conductor 320 may have substantially the same planerdimensions as the glasses 311 and 312 and be arranged across the entireheat-generating plate 310 and may be arranged on a part of theheat-generating plate 310 such as a front portion of a driver's seat inthe example in FIG. 29.

The base film 321 functions as a base material for supporting theheat-generating conductor 330. The base film 321 is a so-calledtransparent electrically insulating substrate for transmitting lightwith a wavelength in a visible light wavelength band (380 nm to 780 nm).As the base film 321, any material can be used as long as the materialcan transmit visible light and appropriately support the heat-generatingconductor 330. For example, polyethylene terephthalate, polyethylenenaphthalate, polycarbonate, polystyrene, and cyclic polyolefine can beexemplified. In consideration of light transmittance and appropriatesupporting property of the heat-generating conductor 330, it ispreferable that the thickness of the base film 321 be equal to or morethan 0.03 mm and equal to or less than 0.20 mm.

Next, the heat-generating conductor 330 will be described with referenceto FIG. 32. FIG. 32 is a plan view illustrating the heat-generatingconductor 330 from the normal direction of the sheet surface. FIG. 32 isa view illustrating an exemplary arrangement of the heat-generatingconductor 330.

As illustrated in FIG. 32, the heat-generating conductor 330 includes aplurality of linear conductive thin wires 331 for coupling the pair ofbus bars 325. The conductive thin wire 331 is energized from the powersupply 307 such as a battery via the wiring portion 315 and the bus bars325 and generates heat by resistance heating. Then, the heat istransmitted to the glasses 311 and 312 via the bonding layers 313 and314 so as to heat the glasses 311 and 312.

In the example illustrated in FIG. 32, the plurality of conductive thinwires 331 extends from one of the bus bars 325 to the other bus bar 325.The plurality of conductive thin wires 331 is arranged separated fromeach other. In particular, the plurality of conductive thin wires 331 isarranged along a direction perpendicular to the extending direction ofthe conductive thin wires 331. A gap 335 is formed between two adjacentconductive thin wires 331.

As a material forming the heat-generating conductor 330, for example,one or more alloys of two or more kinds of metals selected from amongmetals including gold, silver, copper, platinum, aluminum, chromium,molybdenum, nickel, titanium, palladium, indium, and tungsten andnickel-chromium alloy, and bronze can be exemplified.

The heat-generating conductor 330 may be formed by using an opaque metalmaterial as described above. On the other hand, the conductive thin wire331 of the heat-generating conductor 330 is formed with a high uncoatingratio of about equal to or higher than 70% and equal to or lower than99.8%. Therefore, an entire region, in which the conductive thin wire331 and the coupling conductive thin wire 332 of the heat-generatingconductor 330 are formed, is transparent and does not impair visibility.

In the example illustrated in FIG. 31, the conductive thin wire 331 hasa substantially trapezoidal cross section as a whole. More precisely,the side surface of the conductive thin wire 331 has a concave curvedshape to be etched in a manufacturing process to be described later. Itis preferable that a width W of a bottom portion of the conductive thinwire 331, that is, a length along the plate surface of theheat-generating plate 310 be equal to or longer than 11 μm and equal toor shorter than 20 μm and a height (thickness) H, that is, a height(thickness) along a normal direction to the plate surface of theheat-generating plate 310 be equal to or more than 1 μm and equal to orless than 60 μm. According to the conductive thin wire 331 having such asize, since the conductive thin wire 331 is sufficiently thinned, theheat-generating conductor 330 can be effectively made invisible.

As illustrated in FIG. 31, the conductive thin wire 331 includes aconductive metal layer 336, a first dark color layer 337 that covers thesurface of the conductive metal layer 336 facing to the base film 321,and a second dark color layer 338 that covers the surface of theconductive metal layer 336 facing to the glass 311 and side surfaces.

The conductive metal layer 336 formed of a metal material havingexcellent conductivity has a relatively high reflectance. When theconductive metal layer 336 forming the conductive thin wire 331 of theheat-generating conductor 330 reflects light, the reflected light isvisually recognized, and the light may interfere a field of view of apassenger. Furthermore, when the conductive metal layer 336 is visuallyrecognized from outside, design may be deteriorated. Thus, the first andsecond dark color layers 337 and 338 are arranged on at least a part ofthe surface of the conductive metal layer 336. It is preferable that thefirst and second dark color layers 337 and 338 be having lowerreflectance of visible light than the conductive metal layer 336, forexample, the first and second dark color layers 337 and 338 are layersof dark colors such as black. With the dark color layers 337 and 338,the conductive metal layer 336 is hardly and visually recognized, and apassenger's visibility is preferably secured. In addition, thedeterioration in the design when the viewed from outside can beprevented.

As described above, the conductive thin wire 331 of the heat-generatingconductor 330 is formed on the base film 321 with a high uncoating ratiofrom viewpoint of securing visually transmitting performance andvisibility. Therefore, as illustrated in FIG. 31, the bonding layer 313has contact with the base film 321 of the sheet with a conductor 320 viaa non-covered portion of the conductive thin wire 331, that is, a regionbetween the adjacent conductive thin wires 331. Therefore, theheat-generating conductor 330 is embedded in the bonding layer 313.

Incidentally, in FIG. 33, an enlarged view of a part of the conductivethin wire 331 viewed from the normal direction of the sheet surface isillustrated. As a result of intensive investigation by the inventors ofthe present invention, as illustrated in FIG. 33, conductive thin wires331 of a heat-generating conductor 330 that have been actually producedare distributed in a line width W along the longitudinal direction. Sucha tendency has remarkably occurred in the heat-generating conductor 330of the sheet with a conductor 320 produced by a manufacturing method tobe described later with reference to FIGS. 35 to 43. When the inventorsof the present invention have examined a relationship between afluctuation of the line width W and disconnection of the conductive thinwire 331, it has been confirmed that the fluctuation of the line width Wstrongly affects on how easily the conductive thin wire 331 isdisconnected. As a result of confirmation by the inventors of thepresent invention, when it is assumed that an average of the width W ofthe conductive thin wire 331 be W_(ave) and a standard deviation be σ,in a case where the width W is distributed so as to satisfy thefollowing formula(a), the width of the conductive thin wire 331 can beset within a range in which the conductive thin wire 331 of theheat-generating conductor 330 is hardly disconnected and the conductivethin wire 331 is not visually recognized.

0≤4σ/W _(ave)≤0.3  Formula(a)

FIG. 34 is an enlarged view of the conductive thin wire 331 on the sheetwith a conductor 320 viewed from the cross sectional area. In FIG. 34,the conductive metal layer and the dark color layers are omitted. Theconductive thin wire 331 illustrated in FIG. 34 indicates the crosssection of the conductive thin wire 331 produced by a manufacturingmethod to be described later. In the example illustrated in FIG. 34, thewidth W of the conductive thin wire 331 different at each position alongthe normal direction of the sheet with a conductor 320. In the exampleillustrated in FIG. 34, the width W of the conductive thin wire 331 isdifferent at each position along the normal direction of the sheet witha conductor 320. In the conductive thin wire 331 of which the width Wfluctuates along the normal direction of the sheet with a conductor 320,the width W of the conductive thin wire 331 indicates the maximum widthof each cross section that easily affects the disconnection andvisualization. That is, in the example illustrated in FIG. 34, the widthW of the conductive thin wire 331 indicates a width of a bottom portionclosest to the base film 321.

Furthermore, as illustrated in FIG. 33, the conductive thin wire 331 hasa curved line portion, and not only the width of the curved portion butalso a curvature is not constant. In particular, in the illustratedexample, the conductive thin wire 331 is formed by only curved lineportions. Since the conductive thin wire 331 has the curved lineportions, generation of a strong streaky light in a specific directioncaused by diffraction in the conductive thin wire 331, that is, a beamof light can be effectively made inconspicuous.

As illustrated in FIG. 33, the curvature of the curved line portion ofthe conductive thin wire 331 is not constant. Especially, the conductivethin wire 331 includes a “portion with a relatively small curvature(small curvature portion, refer to reference numeral “A” in FIG. 33)”and a “portion with a relatively large curvature (first large curvatureportion, refer to reference numeral “B” in FIG. 33)” of which respectivewidths W of the conductive thin wire 331 are different from each other.The width W of the conductive thin wire 331 is large in a smallcurvature portion A with a relatively small curvature and is small in alarge curvature portion B with a relatively large curvature. As a resultof intensive research by the inventors of the present invention, bymaking the width W of the conductive thin wire 331 be large in the smallcurvature portion A and be small in the large curvature portion B, itcan be effectively prevented that the small curvature portion A isvisually recognized as dots, and as a result, the heat-generatingconductor 330 can be effectively made invisible.

Next, an example of a manufacturing method for the heat-generating plate310 will be described with reference to FIGS. 35 to 43. FIGS. 35 to 38and FIGS. 41 to 43 are cross-sectional views sequentially illustratingthe example of the manufacturing method for the heat-generating plate310. FIGS. 39 and 40 are views for explaining spread of an etchant foretching to be described later.

First, as illustrated in FIG. 35, a dark color film 337 a that forms thefirst dark color layer 337 is formed on the base film 321. As the basefilm 321, any material can be used as long as the material canappropriately hold the heat-generating conductor 330. For example,polyethylene terephthalate, polyethylene naphthalate, polycarbonate,polystyrene, and cyclic polyolefine can be exemplified. In considerationof retention of the heat-generating conductor 330 and the like, it ispreferable to use the base film 321 having the thickness of equal to ormore than 30 μm and equal to or less than 150 μm. Furthermore, the darkcolor film 337 a can be provided, for example, by a plating methodincluding electroplating and electroless plating, a sputtering method, aCVD method, a PVD method, and an ion plating method or a method ofcombination of two or more methods described above. As a material of thedark color film 337 a, various known materials can be used. For example,copper nitride, copper oxide, nickel nitride can be used.

Next, as illustrated in FIG. 36, a metal film 336 a that forms theconductive metal layer 336 is provided on the dark color film 337 a. Asalready described as a material forming the conductive metal layer 336,the metal film 336 a may be formed by using one or more of gold, silver,copper, platinum, aluminum, chromium, molybdenum, nickel, titanium,palladium, indium, and tungsten, and an alloy of these metals. The metalfilm 336 a may be formed by a known method. For example, a method ofbonding a metal foil such as a copper foil, a plating method includingelectroplating and electroless plating, a sputtering method, a CVDmethod, a PVD method, an ion plating method, or a method of combinationof two or more methods described above can be employed.

Next, as illustrated in FIG. 37, a resist pattern 339 is provided on themetal film 336 a, and an etched material (in illustrated example,sheet-like member to be etched) 340 is created. The resist pattern 339has a shape corresponding to the heat-generating conductor 330 to beformed. In the method described here, the resist pattern 339 is providedonly on a portion finally forming the heat-generating conductor 330. Theresist pattern 339 can be formed by patterning using a knownphotolithography technique.

Next, as illustrated in FIG. 38, the metal film 336 a and the dark colorfilm 337 a of the etched material 340 are etched using the resistpattern 339 as a mask. By this etching, the metal film 336 a and thedark color film 337 a are patterned to substantially the same pattern asthe resist pattern 339. As a result, the conductive metal layer 336 thatwill form a part of the conductive thin wire 331 is formed from thepatterned metal film 336 a. The first dark color layer 337 that willform a part of the conductive thin wire 331 and coupling conductive thinwire 332 is formed from the patterned dark color film 337 a.

Here, an etching method will be described with reference to FIGS. 39 and40. First, as illustrated in FIG. 39, the etched material (inillustrated example, sheet-like member to be etched) 340 is moved in adirection of an arrow. At this time, an extending direction of theresist pattern 339, that is, an extending direction of the conductivemetal layer 336 generated after etching is corresponded to a travelingdirection of the etched material 340. Then, to the moving etchedmaterial 340, the etchant is spread from a spray 350 provided above theetched material 340. At this time, while the spray 350 is verticallyshaken relative to the traveling direction of the etched material 340,the etchant is spread. According to this aspect, the etchant can beuniformly spread in a direction perpendicular to the extending directionof the resist pattern 339. Furthermore, by adjusting an amount of spreadetchant from the spray 350 and a traveling speed of the etched material340, a degree of progress of etching relative to the entire etchedmaterial 340 can be adjusted.

When the etchant is spread as described above, since the etchant remainsdiffused in a portion of the resist pattern 339 with a small curvatureas a region A′ in FIG. 40, the progress of etching is relatively slow.Therefore, finally, the width of the conductive metal layer 336 formingthe conductive thin wire 331 is widened. That is, in the small curvatureportion A illustrated in FIG. 33, the line width W of the conductivethin wire 331 is relatively wider. On the other hand, since the etchantconcentrates in a portion of the resist pattern 339 with a largecurvature as a region B′, the progress of etching is relatively fast.Therefore, finally, the width of the conductive metal layer 336 formingthe conductive thin wire 331 is narrowed. That is, in the largecurvature portion B illustrated in FIG. 33, the line width W of theconductive thin wire 331 is relatively thinner. That is, with theetching method illustrated in FIG. 39, by adjusting the amount of spreadetchant from the spray 350 and the traveling direction of the etchedmaterial 340, the width W of the conductive thin wire 331 can becontrolled according to the curvature of the resist pattern 339, thatis, the curvature of the conductive thin wire 331 to be formed.

In this way, according to the amount of spread etchant of the resistpattern 339 and the traveling speed of the etched material 340, thewidth of the conductive metal layer 336 finally forming the conductivethin wire 331 can be easily adjusted. The etching is adjusted so as notto excessively proceeded in a portion of the resist pattern 339 with alarge curvature. As described above, the etched material 340 is etched,and the conductive metal layer 336 and the first dark color layer 337are formed. After that, as illustrated in FIG. 41, the resist pattern339 is removed.

Next, as illustrated in FIG. 42, a second dark color layer 338 is formedon a surface 331 a opposite to a surface 331 b of the conductive metallayer 336 on which the first dark color layer 337 is provided and sidesurfaces 331 c and 331 d. By performing darkening processing (blackeningprocessing) on a part of the material forming the conductive metal layer336, the second dark color layer 338 formed of metal oxide or metalsulfide can be formed from a part of the conductive metal layer 336.Furthermore, the second dark color layer 338 may be provided on thesurface of the conductive metal layer 336 as a coating film of a darkcolor material and a plating layer of nickel or chromium. In addition,the second dark color layer 338 may be provided by roughening thesurface of the conductive metal layer 336. According to the aboveprocess, the sheet with a conductor 320 is produced.

Finally, as illustrated in FIG. 43, the bonding layer 313 and the glass311 are laminated from the side of the heat-generating conductor 330 ofthe sheet with a conductor 320, and the sheet with a conductor 320 isbonded to the glass 311 by heating and pressurizing. Similarly, bylaminating the bonding layer 314 and the glass 312 from the side of thebase film 321, the sheet with a conductor 320 is bonded to the glass312. Accordingly, the heat-generating plate 310 illustrated in FIG. 31is produced.

As described above, the heat-generating plate 310 according to thepresent embodiment is a heat-generating plate that generates heat when avoltage is applied and includes the pair of glasses 311 and 312, thepair of bus bars 325 to which the voltage is applied, and theheat-generating conductors 330 for coupling between the pair of bus bars325, and the heat-generating conductor 330 includes the plurality ofconductive thin wires 331 that linearly extends between the pair of busbars 325 and couples the bus bars 325, and the average W_(ave) of thewidth W of the bottom portion of the conductive thin wire 331 is withina range of the following formula(a) relative to the standard deviation σof the distribution of the width W.

0≤4 σ/W _(ave)≤0.3  Formula(a)

According to the heat-generating plate 310, a difference of the width Wof the bottom portion of the conductive thin wire 331 is small as awhole, disconnection of the conductive thin wire 331 of theheat-generating conductor 330 hardly occurs, and the width of theconductive thin wire 331 can be set within a range in which theconductive thin wire 331 is not visually recognized. Therefore, unevenheat hardly occurs in the heat-generating plate 310, and an excellentvisual field through the heat-generating plate 310 can be obtained.

In the heat-generating plate 310 according to the present embodiment,the conductive thin wire 331 includes a large curvature portion B inwhich a curvature of a pattern in a plan view is relatively large and asmall curvature portion A in which a curvature of a pattern in a planview is relatively small. The width W of the conductive thin wire 331 issmall in the large curvature portion B and large in the small curvatureportion A. According to the present embodiment, the heat-generatingconductor 330 can be effectively made invisible.

The heat-generating plate 310 may be used for the front window, the sidewindow, or the sunroof of the automobile 301. In addition, theheat-generating plate 310 may be used for a window or a transparent doorof a vehicle such as a railway vehicle, an aircraft, a ship, and aspacecraft other than the automobile.

Furthermore, other than the vehicle, the heat-generating plate 310 canbe particularly used as a window for a building such as a window or atransparent door of a place for dividing a space into indoor andoutdoor, for example, a building and a house.

Noted that various modifications can be made to the embodiment.

Fifth Embodiment

FIGS. 44 to 54 are views for explaining one embodiment of the presentinvention. FIG. 44 is a view schematically illustrating an automobileincluding a heat-generating plate, FIG. 45 is a view of theheat-generating plate viewed from the normal direction of the platesurface, and FIG. 46 is a cross-sectional view of the heat-generatingplate in FIG. 45.

As illustrated in FIG. 44, an automobile 401 as an example of a vehicleincludes a window glass such as a front window, a rear window, and aside window. Here, an example in which a front window 405 is configuredby a heat-generating plate 410 will be described. In addition, theautomobile 401 includes a power supply 407 such as a battery.

As illustrated in FIGS. 45 and 46, the heat-generating plate 410according to the present embodiment includes a pair of glasses 411 and412, a sheet with a conductor 420 arranged between the pair of glasses411 and 412, and a pair of bonding layers 413 and 414 for bonding therespective glasses 411 and 412 to the sheet with a conductor 420. In theexamples illustrated in FIGS. 44 and 45, the heat-generating plate 410and the glasses 411 and 412 are curved. However, in other drawings, foreasy understanding, the heat-generating plate 410 and the glasses 411and 412 having plate-like shapes are illustrated.

The sheet with a conductor 420 includes a base film 421, bus bars 425,and a heat-generating conductor 430 provided on a surface facing to theglass 411 of the base film 421. The heat-generating conductor 430includes main conductive thin wires 431 and coupling conductive thinwires 432 for connecting the main conductive thin wires 431.

As illustrated in FIG. 45, the heat-generating plate 410 includes awiring portion 415 for energizing the heat-generating conductor 430 ofthe sheet with a conductor 420 via the bus bars 425. In the illustratedexample, the power supply 407 such as a battery supplies power to theheat-generating conductor 430 via the wiring portion 415 and the busbars 425, and the main conductive thin wire 431 and the couplingconductive thin wire 432 of the heat-generating conductor 430 are heatedby resistance heating. Heat generated by the heat-generating conductor430 is transmitted to the glasses 411 and 412 and heat the glasses 411and 412. As a result, fogging due to dew condensation attached on theglasses 411 and 412 can be removed. In a case where snow or ice isattached on the glasses 411 and 412, snow and ice can be melted.Therefore, a passenger's visibility is preferably secured.

Each component of the heat-generating plate 410 will be described below.

First, the glasses 411 and 412 will be described. When the glasses 411and 412 are used for a front window of an automobile as in the exampleillustrated in FIG. 44, it is preferable to use a glass with a highvisible light transmittance so as not to interfere the field of view ofa passenger. As a material of the glasses 411 and 412, soda-lime glassand blue plate glass can be used. It is preferable that a transmittanceof the glasses 411 and 412 in a visible light region be equal to orhigher than 90%. Here, the visible light transmittance of the glasses411 and 412 is specified as an average value of transmittances inrespective wavelengths when the transmittance is measured by aspectrophotometer (“UV-3100PC” manufactured by SHIMADZU CORPORATION,conforming to JIS K 0115) within a measurement wavelength range of 380nm to 780 nm. The visible light transmittance may be lowered by coloringa part of or all of the glasses 411 and 412. In this case, directsunlight can be shielded, and it is possible to make it difficult tovisually recognize an interior of the vehicle from the outside of thevehicle.

Furthermore, it is preferable that the glasses 411 and 412 have athickness of equal to or more than 1 mm and equal to or less than 5 mm.With such a thickness, the glasses 411 and 412 having excellent strengthand optical characteristics can be obtained. The pair of glasses 411 and412 may be formed of the same material and with the same structure, orat least one of the material and the structure may be different.

Next, the bonding layers 413 and 414 will be described. The bondinglayer 413 is arranged between the glass 411 and the sheet with aconductor 420 and bonds the glass 411 to the sheet with a conductor 420.The bonding layer 414 is arranged between the glass 412 and the sheetwith a conductor 420 and bonds the glass 412 to the sheet with aconductor 420.

As such bonding layers 413 and 414, a layer formed of a material havingvarious adhesiveness and viscosity can be used. Furthermore, it ispreferable to use a material having a high visible light transmittancefor the bonding layers 413 and 414. As a typical bonding layer, a layerformed of polyvinyl butyral (PVB) can be exemplified. It is preferablethat the thickness of each of the bonding layers 413 and 414 be equal toor more than 0.15 mm and equal to or less than 1 mm. The pair of bondinglayers 413 and 414 may be formed of the same material and with the samestructure, or at least one of the material and the structure may bedifferent.

The heat-generating plate 410 is not limited to the illustrated example,and other function layer that is expected to perform a specific functionmay be provided. Furthermore, one function layer may perform two or morefunctions, and for example, some function may be added to at least oneof the glasses 411 and 412 of the heat-generating plate 410, the bondinglayers 413 and 414, and the base film 421 of the sheet with a conductor420 to be described later. As an example of the function that can beapplied to the heat-generating plate 410, an anti-reflection (AR)function, a hard coating (HC) function having scratch resistance, aninfrared ray shielding (reflection) function, an ultraviolet rayshielding (reflection) function, and an antifouling function can beexemplified.

Next, the sheet with a conductor 420 will be described. The sheet with aconductor 420 includes a base film 421, bus bars 425, and aheat-generating conductor 430 provided on a surface facing to the glass411 of the base film 421. The heat-generating conductor 430 includes themain conductive thin wires 431 and the coupling conductive thin wires432. The sheet with a conductor 420 may have substantially the sameplaner dimensions as the glasses 411 and 412 and be arranged across theentire heat-generating plate 410 and may be arranged on a part of theheat-generating plate 410 such as a front portion of a driver's seat inthe example in FIG. 44.

The base film 421 functions as a base material for supporting theheat-generating conductor 430. The base film 421 is a so-calledtransparent electrically insulating substrate for transmitting lightwith a wavelength in a visible light wavelength band (380 nm to 780 nm).As the base film 421, any material can be used as long as the materialcan transmit visible light and appropriately support the heat-generatingconductor 430. For example, polyethylene terephthalate, polyethylenenaphthalate, polycarbonate, polystyrene, and cyclic polyolefine can beexemplified. In consideration of light transmittance and appropriatesupporting property of the heat-generating conductor 430, it ispreferable that the thickness of the base film 421 be equal to or morethan 0.03 mm and equal to or less than 0.20 mm.

Next, the heat-generating conductor 430 will be described with referenceto FIG. 47. FIG. 47 is a plan view illustrating the heat-generatingconductor 430 from the normal direction of the sheet surface. FIG. 47 isa view illustrating an exemplary arrangement of the heat-generatingconductor 430.

As illustrated in FIG. 47, the heat-generating conductor 430 includes aplurality of linear main conductive thin wires 431 for coupling a pairof bus bars 425 and coupling conductive thin wires 432 for coupling twoadjacent main conductive thin wires 431. The main conductive thin wire431 and the coupling conductive thin wire 432 are energized from thepower supply 407 such as a battery via the wiring portion 415 and thebus bars 425 and generate heat by resistance heating. Then, the heat istransmitted to the glasses 411 and 412 via the bonding layers 413 and414 so as to heat the glasses 411 and 412.

In the example illustrated in FIG. 47, each of the plurality of mainconductive thin wires 431 has a regular structure and extends from oneof the bus bars 425 to the other bus bar 425. The main conductive thinwires 431 are arranged separated from each other. Accordingly, a gap 435is formed between the two adjacent main conductive thin wires 431.

The arrangement pattern of each main conductive thin wire 431 is notlimited to the pattern in FIG. 47 and may be a straight line, apolygonal line, an irregular curve, or a combination of these patterns.Furthermore, the main conductive thin wires 431 may extend from one ofthe bus bars 425 to the other bus bar 425 in different patterns.

As illustrated in FIG. 47, the coupling conductive thin wire 432 isarranged in the gap 435 between the two adjacent main conductive thinwires 431 so as to couple the two adjacent main conductive thin wires431. Therefore, when the coupling conductive thin wire 432 is arranged,the two adjacent main conductive thin wires 431 are electricallyconnected to each other. Therefore, even if the main conductive thinwire 431 is disconnected, electrical connection is maintained. Thecoupling conductive thin wire 432 has a shape of a straight line, acircular arc, or a combination of a straight line and a circular arc.Furthermore, each coupling conductive thin wire 432 has a patterndifferent from three or more coupling conductive thin wires 432, orpreferably, all the other coupling conductive thin wires 432. Here, thedifference in the patterns of the coupling conductive thin wires 432means that at least one of the shape of the conductive thin wire and adirection in which both ends of the coupling conductive thin wires arecoupled is different between the compared coupling conductive thin wires432. That is, if the directions in which both ends are coupled of thecompared coupling conductive thin wires 432 are different from eachother, even when the shapes of the coupling conductive thin wires 432are the same, or if the shapes are different even when the directions inwhich both ends are connected are the same, it is assumed that thepatterns of the coupling conductive thin wires 432 be different fromeach other.

As a material forming the heat-generating conductor 430, for example,one or more alloys of two or more kinds of metals selected from amongmetals including gold, silver, copper, platinum, aluminum, chromium,molybdenum, nickel, titanium, palladium, indium, and tungsten andnickel-chromium alloy, and bronze can be exemplified.

The heat-generating conductor 430 may be formed by using an opaque metalmaterial as described above. On the other hand, the main conductive thinwire 431 and the coupling conductive thin wire 432 of theheat-generating conductor 430 are formed with a high uncoating ratio ofabout equal to or higher than 70% and equal to or lower than 99.8%.Therefore, an entire region in which the main conductive thin wires 431and the coupling conductive thin wires 432 of the heat-generatingconductor 430 are formed is transparent and does not impair visibility.

In the example illustrated in FIG. 46, each of the main conductive thinwire 431 and the coupling conductive thin wire 432 has a rectangularcross section as a whole. It is preferable that the widths W of the mainconductive thin wire 431 and the coupling conductive thin wire 432, thatis, the width W along the plate surface of the heat-generating plate 410be equal to or more than 2 μm and equal to or less than 20 μm and thatthe height (thickness) H, that is, the height (thickness) H along thenormal direction to the plate surface of the heat-generating plate 410be equal to or more than 1 μm and equal to or less than 60 μm. Accordingto the main conductive thin wire 431 and the coupling conductive thinwire 432 having such a size, since the main conductive thin wire 431 andthe coupling conductive thin wire 432 are sufficiently thinned, theheat-generating conductor 430 can be effectively made invisible.

As illustrated in FIG. 46, each of the main conductive thin wire 431 andthe coupling conductive thin wire 432 includes a conductive metal layer436, a first dark color layer 437 that covers the surface of theconductive metal layer 436 facing to the base film 421, and a seconddark color layer 438 that covers the surface of the conductive metallayer 436 facing to the glass 411 and both side surfaces.

The conductive metal layer 436 formed of a metal material havingexcellent conductivity has a relatively high reflectance. When theconductive metal layer 436 forming the main conductive thin wire 431 andthe coupling conductive thin wire 432 of the heat-generating conductor430 reflects light, the reflected light is visually recognized, and thelight may interfere a field of view of a passenger. Furthermore, whenthe conductive metal layer 436 is visually recognized from outside,design may be deteriorated. Thus, the first and second dark color layers437 and 438 are arranged on at least a part of the surface of theconductive metal layer 436. It is preferable that the first and seconddark color layers 437 and 438 have a lower reflectance of visible lightthan the conductive metal layer 436, for example, the first and seconddark color layers 437 and 438 are layers of dark colors such as black.With the dark color layers 437 and 438, the conductive metal layer 436is hardly and visually recognized, and a passenger's visibility ispreferably secured. In addition, the deterioration in the design whenthe viewed from outside can be prevented.

As described above, the main conductive thin wire 431 and the couplingconductive thin wire 432 of the heat-generating conductor 430 are formedon the base film 421 with a high uncoating ratio from viewpoint ofsecuring visually transmitting performance and visibility. Therefore, asillustrated in FIG. 46, the bonding layer 413 has contact with the basefilm 421 of the sheet with a conductor 420 via a non-covered portionthat is not covered with the main conductive thin wire 431 and thecoupling conductive thin wire 432, that is, regions where the mainconductive thin wire 431 and the coupling conductive thin wire 432 arenot provided. Therefore, the heat-generating conductor 430 is embeddedin the bonding layer 413.

Next, an example of a manufacturing method for the heat-generating plate410 will be described with reference to FIGS. 48 to 54. FIGS. 48 to 54are cross-sectional views sequentially illustrating the example of themanufacturing method for the heat-generating plate 410.

First, as illustrated in FIG. 48, a dark color film 437 a that forms thefirst dark color layer 437 is formed on the base film 421. As the basefilm 421, any material can be used as long as the material canappropriately hold the heat-generating conductor 430. For example,polyethylene terephthalate, polyethylene naphthalate, polycarbonate,polystyrene, and cyclic polyolefine can be exemplified. In considerationof retention of the heat-generating conductor 430 and the like, it ispreferable to use the base film 421 having the thickness of equal to ormore than 30 μm and equal to or less than 150 μm. Furthermore, the darkcolor film 437 a can be provided by a method, for example, a platingmethod including electroplating and electroless plating, a sputteringmethod, a CVD method, a PVD method, and an ion plating method or amethod of combination of two or more methods described above. As amaterial of the dark color film 437 a, various known materials can beused. For example, copper nitride, copper oxide, nickel nitride can beused.

Next, as illustrated in FIG. 49, a metal film 436 a that forms theconductive metal layer 436 is provided on the dark color film 437 a. Asalready described as a material forming the conductive metal layer 436,the metal film 436 a may be formed by using one or more of gold, silver,copper, platinum, aluminum, chromium, molybdenum, nickel, titanium,palladium, indium, and tungsten, and an alloy of these metals. The metalfilm 436 a may be formed by a known method. For example, a method ofbonding a metal foil such as a copper foil, a plating method includingelectroplating and electroless plating, a sputtering method, a CVDmethod, a PVD method, an ion plating method, or a method of combinationof two or more methods described above can be employed.

Next, as illustrated in FIG. 50, a resist pattern 439 is provided on themetal film 436 a. The resist pattern 439 has a shape corresponding tothe heat-generating conductor 430 to be formed. In the method describedhere, the resist pattern 439 is provided only on a portion finallyforming the heat-generating conductor 430. The resist pattern 439 can beformed by patterning using a known photolithography technique.

Next, as illustrated in FIG. 51, the metal film 436 a and the dark colorfilm 437 a are etched using the resist pattern 439 as a mask. By thisetching, the metal film 436 a and the dark color film 437 a arepatterned to substantially the same pattern as the resist pattern 439.As a result, the conductive metal layer 436 that will form a part of themain conductive thin wire 431 and the coupling conductive thin wire 432is formed from the patterned metal film 436 a. The first dark colorlayer 437 that will form a part of the main conductive thin wire 431 andthe coupling conductive thin wire 432 is formed from the patterned darkcolor film 437 a.

An etching method is not particularly limited, and a known method can beemployed. As a known method, for example, wet etching using an etchantand plasma etching can be exemplified. Particularly, in wet etching in a“role-to-role” manner, existence of the coupling conductive thin wire432 can effectively prevent collapse and peeling of the conductive metallayer 436 and the first dark color layer 437 caused by being conveyed.After that, as illustrated in FIG. 52, the resist pattern 439 isremoved.

Next, as illustrated in FIG. 53, a second dark color layer 438 is formedon a surface 431 a opposite to a surface 431 b of the conductive metallayer 436 on which the first dark color layer 437 is provided and sidesurfaces 431 c and 431 d. By performing darkening processing (blackeningprocessing), for example, on a part of the material forming theconductive metal layer 436, the second dark color layer 438 formed ofmetal oxide or metal sulfide can be formed from a part of the conductivemetal layer 436. Furthermore, the second dark color layer 438 may beprovided on the surface of the conductive metal layer 436 as a coatingfilm of a dark color material and a plating layer of nickel or chromium.In addition, the second dark color layer 438 may be provided byroughening the surface of the conductive metal layer 436. According tothe above process, the sheet with a conductor 420 is produced.

Finally, as illustrated in FIG. 54, the bonding layer 413 and the glass411 are laminated from the side of the heat-generating conductor 430 ofthe sheet with a conductor 420, and the sheet with a conductor 420 isbonded to the glass 411, for example, by heating and pressurizing.Similarly, by laminating the bonding layer 414 and the glass 412 fromthe side of the base film 421, the sheet with a conductor 420 is bondedto the glass 412. Accordingly, the heat-generating plate 410 illustratedin FIG. 46 is produced.

As described above, the heat-generating plate 410 according to thepresent embodiment is a heat-generating plate that generates heat when avoltage is applied and includes the pair of glasses 411 and 412, thepair of bus bars 425 to which the voltage is applied, and theheat-generating conductor 430 for coupling between the pair of bus bars425, and the heat-generating conductor 430 includes the plurality ofmain conductive thin wires 431 that linearly extends between the pair ofbus bars 425 and couples the bus bars 425 and the coupling conductivethin wires 432 that couples between the two adjacent main conductivethin wires 431, and each coupling conductive thin wire 432 has three ormore different patterns. According to such a heat-generating plate 410,even when a certain position of the main conductive thin wire 431 isdisconnected, electrical connection of the main conductive thin wire 431can be maintained by the coupling conductive thin wire 432. Therefore,occurrence of uneven heat caused by disconnection can be prevented. Inaddition, since the coupling conductive thin wire 432 has three or moredifferent patterns, the coupling conductive thin wire 432 is unlikely tohave directivity in a specific direction. Therefore, when the entireheat-generating plate 410 is observed, an orientation direction of thecoupling conductive thin wire 432 becomes inconspicuous. In addition,since the coupling conductive thin wire 432 has three more differentpatterns, a direction of a diffraction image generated by the couplingconductive thin wire 432 is different from a direction of a diffractionimage generated by the other coupling conductive thin wire 432. That is,a direction in which the diffraction image grows stronger is hardlygenerated in the whole coupling conductive thin wire 432. Therefore,strong streaky light, that is, a beam of light does not occur in aspecific direction. Therefore, deterioration in visibility through theheat-generating plate 410 can be avoided.

In addition, in the heat-generating plate 410 according to the presentembodiment, each coupling conductive thin wire 432 has a patterndifferent from those of all the other coupling conductive thin wires432. According to such a heat-generating plate 410, an effect such thata beam of light hardly occurs in the specific direction and an effectsuch that the coupling conductive thin wire 432 is inconspicuous in aspecific arrangement direction can be more enhanced. Therefore, aneffect for avoiding the deterioration of the visibility through theheat-generating plate 410 can be more enhanced.

The heat-generating plate 410 may be used for the front window, the sidewindow, or the sunroof of the automobile 401. In addition, theheat-generating plate 410 may be used for a window or a transparent doorof a vehicle such as a railway vehicle, an aircraft, a ship, and aspacecraft other than the automobile.

Furthermore, the heat-generating plate 410 can be particularly used as awindow for a building such as a window or a transparent door of a placefor dividing a space into indoor and outdoor, for example, a buildingand a house other than a vehicle.

Noted that various modifications can be made to the embodiment.

Sixth Embodiment

FIG. 55 is a plan view of a conductive heat-generating body 505according to an embodiment of the present invention. The conductiveheat-generating body 505 in FIG. 55 includes, for example, aheat-generating body row 533 including a plurality of curvedheat-generating bodies 532 arranged in a range 531 of 80 mm square. Asillustrated in FIG. 56, a plurality of heat-generating body rows 533 isarranged in each of vertical and horizontal directions. The length of 80mm is an example, and the value can be arbitrarily changed. As will bedescribed later, in the present embodiment, shapes of the curvedheat-generating bodies 532 included in the single heat-generating bodyrow 533 are irregularly formed. However, when the heat-generating bodyrows 533 are arranged in the vertical and horizontal directions, eachcurved heat-generating body 532 has a periodic structure in a unit ofthe heat-generating body row 533.

Even when each curved heat-generating body 532 has a periodic structure,to make a beam of light and flicker be inconspicuous, it has been knownthat the size of the heat-generating body row 533 is increased to acertain degree. Specifically, when a length of a side of theheat-generating body row 533 exceeds 50 mm, even when the plurality ofheat-generating body rows 533 is arranged in the vertical and horizontaldirections, a beam of light and flicker are inconspicuous. Hereinafter,as an example, the vertical and horizontal sizes of the heat-generatingbody row 533 are set to 80 mm.

Each curved heat-generating body 532 included in the heat-generatingbody row 533 is a linear heating wire formed of a conductive materialsuch as tungsten and copper. A line width of each curved heat-generatingbody 532 is, for example, 5 to 20 μm, and preferably, 7 to 10 μm. Tomake it difficult to visually recognize the plurality of curvedheat-generating bodies 532 arranged on a transparent base material, itis desirable that the line width of the curved heat-generating body 532be equal to or less than 15 μm. However, as the line width decreases,disconnection tends to occur. Therefore, to prevent the disconnection,it is preferable to secure the line width of equal to or more than 10μm.

The curved heat-generating bodies 532 in FIG. 55 are arranged separatedfrom each other in a first direction x and extend in a second directiony intersecting with the first direction x. In FIG. 55, although anexample is illustrated in which the first direction x and the seconddirection y are perpendicular to each other, an angle between the twodirections is not necessarily a right angle.

Each curved heat-generating body 532 in FIG. 55 is obtained bysequentially connecting a plurality of periodic curved lines of whichperiods and amplitudes are irregular for each period (for example, sinewaves) to each other in the second direction y. In FIG. 55, an exampleis illustrated in which the periodic curved line is a sine wave.However, a plurality of arbitrary periodic curved lines other than sinewaves may be connected to each other. Although a kind of the periodiccurved line is arbitrary, the kinds of connected periodic curved linesare the same, and the period and the amplitude are irregular for eachperiod. The sine wave is referred to as a sinusoidal wave. A generalformula expressed in a coordinate system XY as illustrated in FIG. 55 isX=A sin{(2η/λ)X+α}. Here, a reference numeral A indicates an amplitude,a reference numeral λ indicates a wavelength (or period, and a referencenumeral α indicates a phase. Furthermore, as a periodic curved lineother than a sine wave, an elliptic function curve, a Bessel functioncurve, and the like can be exemplified.

Here, the term “irregular” means that the period and the amplitude ofthe periodic curved line are random for each period, and the periods andthe amplitudes of the periodic curved lines do not have periodicity inthe range 531 of 80 mm square. The periods and the amplitudes of thecurved heat-generating bodies 532 arranged apart from each other in thefirst direction x are irregular.

In this way, the plurality of curved heat-generating bodies 532 arrangedin 80 mm square has irregular periods and amplitudes in the firstdirection x and the second direction y.

When it is assumed that a lower left corner in FIG. 55 be an origin (0,0) and a start point of each of the curved heat-generating bodies 532(head position) be the minimum coordinate position in the seconddirection y, the start positions of the curved heat-generating bodies532, arranged separated from each other along the first direction x, inthe second direction y are irregular. This indicates that the phases ofthe curved heat-generating bodies 532 are irregularly shifted from eachother.

The reason for irregularly shifting the phases of the curvedheat-generating bodies 532 is as follows. For example, when it isassumed that all the start points of the curved heat-generating bodies532 be a coordinate position y=0 in the second direction y, theamplitude of each curved heat-generating body 532 is zero at thecoordinate position y=0. Therefore, when it is assumed that theplurality of heat-generating body rows 533 of 80 mm square be arrangedin the first direction x and the second direction y, in eachheat-generating body row 533, a position where the amplitudes of thecurved heat-generating bodies 532 are zero periodically appears, andthis position may cause a beam of light and flicker.

Therefore, in the present embodiment, by irregularly shifting theminimum coordinate positions of the curved heat-generating bodies 532included in the heat-generating body row 533 of 80 mm square in thesecond direction y, the phases of the curved heat-generating bodies 532are randomized.

As described above, in the present embodiment, for example, since theperiods and the amplitudes of the curved heat-generating bodies 532 areformed to be irregular in the first direction x and the second directiony in the range 531 of 80 mm square, there is less possibility thatreflected light beams reflected by the curved heat-generating bodies 532are interfered with each other, and occurrence of a beam of light can beprevented. In addition, since each curved heat-generating body 532meanders and a meandering sizes are irregular, a traveling direction ofthe reflected light reflected by each curved heat-generating body 532 isirregular, and strong flicker in a specific direction is hardly felt.

In the present embodiment, uneven heat is prevented, for example, ineach heat-generating body row 533 of 80 mm square.

Generally, as a curve of the curved heat-generating body 532 is gentler,that is, as the curve is closer to a straight line, a heat generationefficiency increases. Therefore, from the viewpoint of improving theheat generation efficiency, it is desirable to lengthen the period ofthe curved heat-generating body 532 and narrow the amplitude. On theother hand, from the viewpoint of preventing a beam of light andflicker, it is preferable to shorten the period of the curvedheat-generating body 532 and widen the amplitude. Since both conditionsconflict with each other, it is desirable to set the period and theamplitude of the curved heat-generating body 532 in consideration ofboth the heat generation efficiency and the prevention of a beam oflight and flicker.

If the periods and the amplitudes of the curved heat-generating bodies532 of 80 mm square are set in consideration of only the prevention of abeam of light and flicker, some places have a large heating value andsome places have a small heating value in the range 531 of 80 mm square,and uneven heat may occur.

Therefore, in the present embodiment, a ratio of the length of eachcurved heat-generating body 532 in the second direction y and a lineardistance (=80 mm) of the range 531 of 80 mm square in the seconddirection y is within a range between a predetermined upper limit and apredetermined lower limit. According to the examination by theinventors, the upper limit of the ratio with which uneven heat does notoccur and a beam of light and flicker can be prevented to a practicallyacceptable level is 1.5, and the lower limit is 1.0.

From this fact, in the present embodiment, a ratio of the length of eachcurved heat-generating body 532 relative to a shortest distance of eachcurved heat-generating body 532 in 80 mm square is set to be larger than1.0 and set to 1.5. While maintaining the ratio, by making the periodsand the amplitudes of the curved heat-generating bodies 532 in 80 mmsquare be irregular and irregularly setting the start point coordinatepositions of the curved heat-generating bodies 532 in the seconddirection y, a beam of light and flicker can be effectively prevented.

Regarding the length L of the curved heat-generating body 532, when itis assumed that a start point coordinate of the curved heat-generatingbody 532 in the second direction y be y0, a terminate point coordinatebe y1, and the shortest distance between both end points of the curvedheat-generating body 532 in the second direction y be D, it is necessaryto set the ratio within a range indicated by the following expression(1).

$\begin{matrix}\left\lbrack {{Expression}\mspace{14mu} 1} \right\rbrack & \; \\{1.0 < {\frac{1}{D}{\int_{y = {y\; 0}}^{y = {y\; 1}}{\sqrt{1 + \left( \frac{dx}{dy} \right)^{2}}{dy}}}} \leq 1.5} & (1)\end{matrix}$

According to further examination by the inventors, it has been foundthat the ratio with which uneven heat does not occur and a beam of lightand flicker can be prevented has a lower limit of 1.01 and an upperlimit of 1.15. That is, it has been found that an optimal range of theratio is expressed by the following expression (2).

$\begin{matrix}\left\lbrack {{Expression}\mspace{14mu} 2} \right\rbrack & \; \\{1.01 < {\frac{1}{D}{\int_{y = {y\; 0}}^{y = {y\; 1}}{\sqrt{1 + \left( \frac{dx}{dy} \right)^{2}}{dy}}}} \leq 1.15} & (2)\end{matrix}$

Furthermore, as the line width of the curved heat-generating body 532 isnarrowed, the curved heat-generating body 532 is more hardly andvisually recognized. Therefore, the narrower line width is preferablewhen the curved heat-generating body 532 is incorporated in a windowglass and the like. However, the curved heat-generating body 532 iseasily disconnected. Therefore, in the present embodiment, the twocurved heat-generating bodies 532 adjacent to each other in the seconddirection y may be connected with a bypass heat-generating body 534.When the bypass heat-generating bodies 534 are periodically arranged,this may cause a beam of light and flicker. Therefore, the bypassheat-generating bodies 534 are irregularly arranged. In addition, thebypass heat-generating bodies 534 are equally arranged in theheat-generating body row 533 within the range 531 of 80 mm square sothat the bypass heat-generating body 534 does not cause uneven heat.

The periods and the amplitudes of the curved heat-generating bodies 532included in the heat-generating body row 533 can be automaticallygenerated by using a computer. FIG. 57 is a block diagram illustrating aschematic configuration of a heat-generating body generating device 541that automatically generates the plurality of curved heat-generatingbodies 532 included in the heat-generating body row 533. Theheat-generating body generating device 541 in FIG. 57 includes aparameter acquiring unit 542, a curved heat-generating body generatingunit 543, a normalizing unit 544, a heat unevenness determining unit545, a curved heat-generating body storing unit 546, a heat-generatingbody group generating unit 547, a phase adjusting unit 548, and aheat-generating body row storing unit 549.

The heat-generating body generating device 541 in FIG. 57 can berealized as software that can be executed by a computer. Alternatively,at least a part of components in the heat-generating body generatingdevice 541 in FIG. 57 may be realized by hardware. That is, theheat-generating body generating device 541 in FIG. 57 is not necessarilyrealized by a single computer.

The parameter acquiring unit 542 acquires a parameter group includingvarious parameters representing features of shape of the curvedheat-generating bodies 532. The parameter acquiring unit 542 may storethe parameter group in a database and the like in advance and acquire anecessary parameter from the stored parameter group or may acquire eachparameter that is input or selected by an operator with a keyboard, amouse, and the like.

For example, the following items 1) to 7) are considered as examples ofthe parameters included in the parameter group.

1) Minimum distance and maximum distance between two curvedheat-generating bodies 532 adjacent to each other in first direction x.

2) Minimum value and maximum value of amplitude of each curvedheat-generating body 532.

3) Minimum value and maximum value of period of each curvedheat-generating body 532.

4) Minimum value and maximum value of phase of each curvedheat-generating body 532.

5) Minimum value and maximum value of ratio of length of each curvedheat-generating body 532 relative to minimum distance of heat-generatingbody row 533 in the second direction y.

6) Length of heat-generating body row 533 in first direction x andlength in second direction y.

7) Number of curved heat-generating bodies 532 included inheat-generating body row 533.

The curved heat-generating body generating unit 543 generates a singlecurved heat-generating body 532 extending in the second direction y.More specifically, the curved heat-generating body generating unit 543connects the plurality of periodic curved lines, having the periods andthe amplitudes that are irregular for each period, in the seconddirection y and generates the single curved heat-generating body 532.

To match the shortest distance between both ends of the curvedheat-generating body 532 generated by the curved heat-generating bodygenerating unit 543 in the second direction y to 80 mm, the normalizingunit 544 adjusts the periods of the plurality of periodic curved linesincluded in the curved heat-generating body 532.

The heat unevenness determining unit 545 determines whether a ratioobtained by dividing a total length of the curved heat-generating body532 normalized by the normalizing unit 544 in the second direction y bythe shortest distance between the both ends of the curvedheat-generating body 532 is within a predetermined range. Thepredetermined range is, for example, a range in which the ratio islarger than 1.0 and equal to or less than 1.5.

When the heat unevenness determining unit 545 determines that the ratiois not within the predetermined range, the curved heat-generating bodygenerating unit 543 generates the curved heat-generating body 532 again.The curved heat-generating body storing unit 546 stores the curvedheat-generating body 532 of which the ratio is determined to be withinthe predetermined range.

The heat-generating body group generating unit 547 generates theplurality of curved heat-generating bodies 532 included in the range 531of 80 mm square. More specifically, the heat-generating body groupgenerating unit 547 generates the plurality of curved heat-generatingbodies 532 arranged apart from each other in the first direction xwithin the range 531 of 80 mm square in cooperation with the curvedheat-generating body generating unit 543, the heat unevennessdetermining unit 545, and a unit pressure heat-generating body storingunit.

The phase adjusting unit 548 makes the phases of the curvedheat-generating bodies 532 generated by the heat-generating body groupgenerating unit 547 be irregular. More specifically, the phase adjustingunit 548 makes the start positions (head position) of the curvedheat-generating bodies 532 in the second direction y be irregular withinthe range 531 of 80 mm square. The heat-generating body row storing unit549 stores the plurality of curved heat-generating bodies 532 of whichthe phase is made to be irregular by the phase adjusting unit 548.

FIG. 58 is a flowchart illustrating an example of a processing procedureof the heat-generating body generating device 541 in FIG. 57. In thisflowchart, processing for generating the plurality of curvedheat-generating bodies 532 included in the heat-generating body row 533within the range 531 of 80 mm square is performed. Hereinafter, anexample will be described in which the plurality of periodic curvedlines included in the curved heat-generating body 532 is a sine wave.

First, the parameter acquiring unit 542 acquires parameters in 1) to 7)(step S1). Next, the curved heat-generating body generating unit 543sets a start point coordinate of the sine wave in the second direction yto zero (step S2). Next, the curved heat-generating body generating unit543 sets the start point coordinate of the sine wave in the firstdirection x to zero (step S3). Then, the curved heat-generating bodygenerating unit 543 randomly sets a period and an amplitude of the sinewave based on the acquired parameter and generates a sine wave for oneperiod along the second direction y (step S4).

Next, the curved heat-generating body generating unit 543 updates acoordinate position in the second direction y by adding the sine wavefor one period set in step S4 (step S5). Next, the curvedheat-generating body generating unit 543 determines whether the addedlength in the second direction y exceeds 80 mm (step S6). If the lengthdoes not exceed 80 mm, processing in steps S4 to S6 is repeated.

When it is determined that the length exceeds 80 mm in step S6, thenormalizing unit 544 adjusts the period of each sine wave included inthe curved heat-generating body 532 so that the shortest distancebetween both ends of the curved heat-generating body 532 in the seconddirection y is 80 mm (step S7). This operation is called normalizationprocessing. In the normalization processing, the period of each sinewave included in the curved heat-generating body 532 is decreased at thesame ratio.

Next, the heat unevenness determining unit 545 determines whether aratio obtained by dividing a total length of the normalized curvedheat-generating body 532 in the second direction y by the shortestdistance between both ends in the second direction y (for example, 80mm) is within a predetermined range (step S8). Here, for example, it isdetermined whether the ratio is larger than 1.0 and equal to or lessthan 1.5 based on the above expression (1).

If the ratio is not within the predetermined range, the procedurereturns to step 2, and the curved heat-generating body 532 is generatedagain. The reason why the curved heat-generating body 532 is generatedagain in a case where the ratio of the curved heat-generating body 532is not within the predetermined range is because uneven heat may occurin unit of the heat-generating body row 533 of 80 mm square in a casewhere the value of the ratio is largely different.

When it is determined in step S8 that the ratio is within thepredetermined range, the normalized curved heat-generating body 532 isstored in the curved heat-generating body storing unit 546 (step S9).

Next, the heat-generating body group generating unit 547 sets acoordinate position that is shifted in the first direction x by onepitch based on the parameter acquired by the parameter acquiring unit542 (step S10). The size of one pitch is set by the parameter acquiredin step S1.

Next, the heat-generating body group generating unit 547 determineswhether the length in the first direction x exceeds 80 mm (step S11). Ifthe length does not exceed 80 mm, the processing in and after step S2 isrepeated, and a new curved heat-generating body 532 is generated.

When it is determined in step S11 that the length exceeds 80 mm, thephase adjusting unit 548 adjusts to make the phases of the curvedheat-generating bodies 532 included in the heat-generating body row 533be irregular (step S12). Next, the plurality of curved heat-generatingbodies 532 of which the phase has been adjusted is stored in theheat-generating body row storing unit 549 (step S13).

An arbitrary number of heat-generating body rows 533 of 80 mm squaregenerated by the processing procedure in FIG. 58 are aligned in thevertical and horizontal directions as illustrated in FIG. 56 to producethe conductive heat-generating body 505 with an arbitrary size and anarbitrary shape. Although the conductive heat-generating body 505according to the present embodiment can be used for various objects andapplications, an example will be described below in which the conductiveheat-generating body 505 according to the present embodiment isincorporated into a front window, a rear window, a side window, or thelike of a vehicle.

Although not illustrated in the flowchart in FIG. 58, as illustrated inFIG. 59, it is desirable to provide the bypass heat-generating body 534for connecting two adjacent curved heat-generating bodies 532 in thefirst direction x in the conductive heat-generating body 505. Even if anarbitrary curved heat-generating body 532 is disconnected, the bypassheat-generating body 534 can supply current via the curvedheat-generating body 532 adjacent to the disconnected one. The bypassheat-generating body 534 may be generated after generating the pluralityof curved heat-generating bodies 532 in the range 531 of 80 mm square,or at the time when the two curved heat-generating bodies 532 adjacentto each other in the first direction x are generated, the bypassheat-generating body 534 for connecting these two curved heat-generatingbodies 532 may be generated.

The bypass heat-generating body 534 has the same line width (forexample, 5 to 20 μm, preferably 7 to 10 μm) as the curvedheat-generating body 532, and the bypass heat-generating bodies 534 arearranged in the heat-generating body row 533 of 80 mm square at auniform density. By arranging the bypass heat-generating bodies 534 witha uniform density, uneven heat in the heat-generating body row 533 canbe prevented. The bypass heat-generating bodies 534 connected to therespective curved heat-generating bodies 532 are irregularly arranged.

FIG. 60 illustrates an example in which the conductive heat-generatingbody 505 according to the present embodiment is incorporated into afront window 502 of a car. The front window 502 is a laminated glass towhich the conductive heat-generating body 505 is incorporated.

The front window 502 in FIG. 60 includes a pair of glass plates 503 and504 and the conductive heat-generating body 505 arranged between thepair of glass plates 503 and 504. The conductive heat-generating body505 includes two bus bar electrodes (first and second electrodes) 506and 507 and a plurality of wavy line conductors 508 connected to the busbar electrodes. In FIG. 60, each wavy line conductor 508 is illustratedas a straight line, the wavy line conductor 508 is actually formed byconnecting periodic curved lines of which a period and an amplitude areirregular, as illustrated in FIG. 55.

More specifically, the plurality of wavy line conductors 508 is formedby combining the plurality of heat-generating body rows 533 describedabove. That is, both ends of each wavy line conductor 508 arerespectively connected to the two bus bar electrodes 506 and 507, andeach wavy line conductor 508 is formed by connecting single curvedheat-generating bodies 532 in each of the plurality of heat-generatingbody rows 533 arranged in the second direction y as illustrated in FIG.55.

In the example in FIG. 60, the two bus bar electrodes 506 and 507 arearranged along both side of the front window 502 in the longitudinaldirection. However, as illustrated in FIG. 61, it is possible that thetwo bus bar electrodes 506 and 507 are arranged along both sides of thefront window 502 in the short-side direction and the plurality of wavyline conductors 508 is arranged along the longitudinal direction of thefront window 502.

The shapes of the wavy line conductors 508 in FIGS. 60 and 61 areirregular. However, intervals (pitch) between reference lines (brokenline 532 a in FIG. 55) of the wavy line conductors 508 are substantiallyconstant, and the reference lines are substantially parallel. Forexample, eight or less wavy line conductors 508 are arranged per cm ofthe front window 502 in the longitudinal direction. That is, it isdesirable that the pitch of the wavy line conductors 508 be equal to ormore than 0.125 cm.

The plurality of wavy line conductors 508 and the two bus bar electrodes506 and 507 are formed of a common conductive material and areintegrally molded. As the conductive material, for example, copper whichhas excellent conductivity and is easily etched is used. As will bedescribed later, in the present embodiment, the plurality of wavy lineconductors 508 and the two bus bar electrodes 506 and 507 are integrallyformed by photolithography. A conductive material other than copper maybe used as long as the material has excellent conductivity and can beeasily processed by photolithographic etching.

By applying a predetermined voltage between the two bus bar electrodes506 and 507, a current flows into the plurality of wavy line conductors508 between the bus bar electrodes 506 and 507, and a resistancecomponent of each wavy line conductor 508 heats each wavy line conductor508. As a result, the pair of glass plates 503 and 504 is heated, andfogging caused by dew condensation attached on the glass plates can beremoved. In addition, snow or ice attached on the outer glass plate canbe melted. Therefore, a passenger's visibility in the vehicle ispreferably secured. In this way, the conductive heat-generating body 505functions as a defroster electrode.

Since it is necessary for the bus bar electrodes 506 and 507 to applyvoltage to each wavy line conductor 508 without power loss, the width ofeach of the bus bar electrodes 506 and 507 in the short-side directionis larger than the width of each wavy line conductor 508 in theshort-side direction. In the present embodiment, since the patterns ofthe bus bar electrodes 506 and 507 and the wavy line conductors 508 areformed by etching a copper thin film, a width of the pattern for the busbar electrodes 506 and 507 is formed to be larger than a width of thepattern for the wavy line conductor 508.

The voltage to be applied to the two bus bar electrodes 506 and 507 issupplied from the battery 509 mounted on the vehicle, a battery cell, orthe like, for example, as illustrated in FIG. 62.

As illustrated in FIG. 63, the conductive heat-generating body 505 inwhich the plurality of wavy line conductors 508 and the two bus barelectrodes 506 and 507 are integrally molded is formed on a transparentbase material 511. The transparent base material 511 may be sandwichedbetween the pair of glass plates 503 and 504 without peeled off, onlythe conductive heat-generating body 505 from which the transparent basematerial 511 is peeled off may be sandwiched between the pair of glassplates 503 and 504. The transparent base material 511 on which theconductive heat-generating body 505 is formed is referred to as aheating element sheet 512 herein.

The wavy line conductor 508 is formed by connecting a plurality of sinewaves with irregular periods and amplitudes in the second direction y,and the wavy line conductor 508 is formed by etching a copper foil orcoating conductive ink. For example, when the wavy line conductor 508 isformed by etching processing, the side surfaces of the wavy lineconductor 508 are arranged in a direction with an angle close to theright angle with respect to a top surface and a bottom surface.Therefore, when the side surface has a planar shape, reflected lightfrom the side surface travels in a specific direction, and a person inthe specific direction feels strong flicker. However, in the presentembodiment, since the wavy line conductor 508 has an irregularly curvedshape, each side surface has an irregular shape, and strong flicker isnot felt in the specific direction.

FIG. 63 is a cross-sectional view taken along a line LXIII-LXIII in FIG.60 of the front window 502 having the heating element sheet 512, inwhich the conductive heat-generating body 505 is formed on thetransparent base material 511, sandwiched between the pair of glassplates 503 and 504. In a case of FIG. 63, the transparent base material511 of the heating element sheet 512 is bonded on the one curved glassplate 503 via a bonding layer (first bonding layer) 513. On theconductive heat-generating body 505 of the heating element sheet 512,the other glass plate 504 is bonded via a bonding layer (second bondinglayer) 514.

Since the transparent base material 511 of the heating element sheet 512and the conductive heat-generating body 505 are sufficiently thin, theheating element sheet 512 has flexibility, and the glass plates 503 and504 can be stably bonded to each other in a state where the heatingelement sheet 512 is curved along the curved shapes of the curved glassplates 503 and 504.

Particularly, when the glass plates 503 and 504 are used for the frontwindow 502 of a vehicle, it is preferable to use a glass with a highvisible light transmittance so as not to interfere the field of view ofa passenger. As a material of the glass plates 503 and 504, soda-limeglass and blue plate glass can be used. It is preferable that atransmittance of the glass plates 503 and 504 in a visible light regionbe equal to or higher than 90%. Here, the visible light transmittance ofthe glass plates 503 and 504 is specified as an average value oftransmittances in respective wavelengths when the transmittance ismeasured by a spectrophotometer (for example, “UV-3100PC” manufacturedby SHIMADZU CORPORATION, conforming to JISK0115) within a measurementwavelength range of 380 nm to 780 nm. The visible light transmittancemay be lowered by coloring a part of or all of the glass plates 503 and504. In this case, direct sunlight can be shielded, and it is possibleto make it difficult to visually recognize an interior of the vehiclefrom the outside of the vehicle.

Furthermore, it is preferable that the glass plates 503 and 504 have athickness of equal to or more than 1 mm and equal to or less than 5 mm.With such a thickness, a glass plate having excellent strength andoptical characteristics can be obtained.

The glass plates 503 and 504 are bonded to the conductiveheat-generating body 505 formed on the transparent base material 511 viathe respective bonding layers 513 and 514. As such bonding layers 513and 514, a layer formed of a material having various adhesiveness andviscosity can be used. Furthermore, it is preferable to use a materialhaving a high visible light transmittance for the bonding layers 513 and514. As typical bonding layers 513 and 514, a layer formed of polyvinylbutyral (PVB) can be exemplified. It is preferable that the thickness ofeach of the bonding layers 513 and 514 be equal to or more than 0.15 mmand equal to or less than 0.7 mm.

A laminated glass such as a front window 502 is not limited to theillustrated example, and other function layer that is expected toperform a specific function may be provided. Furthermore, one functionlayer may perform two or more functions, and for example, variousfunctions may be applied to at least one of the glass plates 503 and 504of a laminated glass 1, the bonding layers 513 and 514, and thetransparent base material 511. For example, an anti-reflection (AR)function, a hard coating (HC) function having scratch resistance, aninfrared ray shielding (reflection) function, an ultraviolet rayshielding (reflection) function, a polarization function, and anantifouling function can be exemplified.

The transparent base material 511 functions as a base material forsupporting the conductive heat-generating body 505. The transparent basematerial 511 is a so-called transparent electrically insulatingsubstrate for transmitting light with a wavelength in a visible lightwavelength band (380 nm to 780 nm) and includes a thermoplastic resin.

As a thermoplastic resin included in the transparent base material 511as a main component, any resin may be used as long as a thermoplasticresin transmits visible light. For example, an acrylic resin such aspolymethyl methacrylate, a polyolefin resin such as polypropylene, apolyester resin such as polyethylene terephthalate and polyethylenenaphthalate, a cellulose resin such as triacetylcellulose (cellulosetriacetate), polyvinyl chloride, polystyrene, a polycarbonate resin, andan AS resin can be exemplified. Especially, an acrylic resin andpolyethylene terephthalate are preferable because an acrylic resin andpolyethylene terephthalate have excellent optical characteristics andcan be easily molded.

In consideration of retention and a light transmittance of theconductive heat-generating body 505 in production, it is preferable thatthe thickness of the transparent base material 511 be equal to or morethan 0.02 mm and equal to or less than 0.20 mm.

FIG. 64 is a cross-sectional view illustrating a process formanufacturing the conductive heat-generating body 505 and illustrates across-sectional structure in a direction of a line LXIII-LXIII in FIG.60. First, as illustrated in FIG. 64(a), a copper thin film 521 isformed on the transparent base material 511. The thin film 521 can beformed by an electric field copper foil, a rolled copper foil,sputtering, vacuum vapor deposition or the like.

Next, as illustrated in FIG. 64(b), a top surface of the copper thinfilm 521 is covered with a photoresist 522. The photoresist 522 is, forexample, a resin layer having photosensitivity relative to light in aspecific wavelength range, for example, ultraviolet light. The resinlayer may be formed by adhering a resin film or may be formed by coatinga fluid resin. In addition, a specific photosensitive characteristics ofthe photoresist 522 is not particularly limited. For example, as thephotoresist 522, a photocurable photosensitive material may be used, ora light dissolving type photosensitive material may be used.

Subsequently, as illustrated in FIG. 64(c), the photoresist 522 ispatterned to form a resist pattern 523. As a method for patterning thephotoresist 522, various known methods can be employed. However, in thisexample, a resin layer having photosensitivity relative to light in aspecific wavelength range, for example, ultraviolet light is used as thephotoresist 522, and the photoresist 522 is patterned by using knownphotolithography technique. First, on the photoresist 522, a mask onwhich a portion to be patterned is opened or a mask in which a portionto be patterned is shielded is arranged. As described above, on themask, a pattern in which both end faces extending in the longitudinaldirection of the wavy line conductor 508 meander is illustrated.Furthermore, in some cases, a pattern in which the entire wavy lineconductor 508 in the longitudinal direction meanders may be drawn on themask.

Next, the photoresist 522 is irradiated with ultraviolet rays throughthe mask. Thereafter, a portion where ultraviolet rays are shielded bythe mask or a portion irradiated with ultraviolet rays is removed by amethod such as development. Thus, the patterned resist pattern 523 canbe formed. A laser patterning method performed without a mask can beused.

Next, as illustrated in FIG. 64(d), etchant for wet etching is jet froman upper side of the resist pattern 523, and the copper thin film 521which is not covered with the resist pattern 523 is etched and removed,and only a region of the copper thin film 521 covered with the resistpattern 523 is left. Next, as illustrated in FIG. 64(e), by peeling offthe resist pattern 523, the plurality of wavy line conductors 508 andthe two bus bar electrodes 506 and 507 are produced. Thereafter, theplurality of wavy line conductors 508 and the two bus bar electrodes 506and 507 formed on the transparent base material 511 are sandwiched andsealed between the pair of glass plates 503 and 504.

A dark color layer to reduce the reflectance of the conductiveheat-generating body 505 may be formed on the patterned surface of thecopper thin film 521 or on a lower surface of the copper thin film 521.By forming the dark color layer, the reflected light in a case whereexternal light is irradiated on the surface of the wavy line conductor508 can be reduced, and occurrence of flicker can be prevented.

In a case where only the plurality of wavy line conductors 508 is formedby photolithography without integrally molding the bus bar electrodes506 and 507, when the etchant is jetted in an etching process inphotolithography, etching is further processed on both ends of the wavyline conductor 508 in the longitudinal direction than the center part inthe longitudinal direction, and a width between the both ends of thewavy line conductor 508 in the longitudinal direction is reduced toomuch, and the wavy line conductor 508 is not conducted to the bus barelectrodes 506 and 507 or resistances of both ends of the wavy lineconductor 508 in the longitudinal direction are abnormally increased. Onthe other hand, in a case where the plurality of wavy line conductors508 and the two bus bar electrodes 506 and 507 are integrally molded asin the present embodiment, since the etchant flowing from the center ofthe wavy line conductors 508 in the longitudinal direction to both endsis stopped by the bus bar electrodes 506 and 507, the entire wavy lineconductor 508 is evenly immersed in the etchant, and a failure such thatthe both ends of the wavy line conductor 508 in the longitudinaldirection are more etched and removed does not occur.

Furthermore, in the present embodiment, since the plurality of wavy lineconductors 508 and the two bus bar electrodes 506 and 507 are integrallymolded by photolithography, contact property between the wavy lineconductor 508 and the bus bar electrodes 506 and 507 is enhanced, powerloss at bonding portions between the wavy line conductor 508 and the busbar electrodes 506 and 507 is reduced, and a heat generation efficiencyis improved than a case where the plurality of wavy line conductors 508is formed by photolithography in advance and the bus bar electrodes 506and 507 separated from the wavy line conductor 508 are bonded to thewavy line conductor 508.

The heating element sheet 512 produced by the manufacturing process inFIG. 64 is arranged between the pair of curved glass plates 503 and 504.More specifically, a laminated glass is produced by laminating the oneglass plate 503, the bonding layer 513, the heating element sheet 512,the bonding layer 514, the glass plate 504 in this order andpressurizing and heating them.

In the manufacturing process in FIG. 64 described above, an example hasbeen described in which the laminated glass is formed by sealing withthe pair of glass plates 503 and 504 after the wavy line conductor 508and the like is formed on the transparent base material 511 by etchingand the like. However, in this example. The transparent base material511 is included between the pair of glass plates 503 and 504, and thenumber of layers between the pair of glass plates 503 and 504 isincreased, and the increase in the thickness increases the weight, andvisibility may be deteriorated due to a difference between the opticalcharacteristics of the layers. In addition, by including the transparentbase material 511, heat transfer characteristics are deteriorated. Inaddition, since the pair of glass plates 503 and 504 is curved asillustrated in FIG. 63, wrinkles may occur in the transparent basematerial 511.

Therefore, as illustrated in FIG. 65, after the heating element sheet512 in which the conductive heat-generating body 516 including the busbar electrodes 506 and 507 and the wavy line conductor 508 is formed onthe transparent base material 511 via the peeling layer 515 is producedand the heating element sheet 512 is bonded to one glass plate, it ispossible that the transparent base material is peeled off and the otherglass plate is bonded after that. FIGS. 66 to 69 are cross-sectionalviews illustrating an example of a process for manufacturing a laminatedglass using the heating element sheet 512 in FIG. 65.

First, the bonding layer 514 and the glass plate 504 are laminated onthe heating element sheet 512 from a surface on which a heating elementis formed (upper side in FIG. 66), and subsequently, the heating elementsheet 512, the bonding layer 514, and the glass plate 504 are bonded toform a first intermediate member 517. For example, it is possible that alaminate in which the bonding layer 514 and the glass plate 504 arelaminated on the heating element sheet 512 is conveyed into an autoclaveapparatus, the heating element sheet 512, the bonding layer 514, and theglass plate 504 are heated and pressurized, and the laminate is takenout from the autoclave apparatus. In this case, if a pressure in theautoclave apparatus is reduced before the heating element sheet 512, thebonding layer 514, and the glass plate 504 are heated and pressurized,it is possible to prevent bubbles from remaining in the bonding layer514, in an interface between the bonding layer 514 and the heatingelement sheet 512, and an interface between the bonding layer 514 andthe glass plate 503.

As a result, as illustrated in FIG. 66, the first intermediate member517 in which the transparent base material 511, the peeling layer 515,the conductive heat-generating body 516, the bonding layer 514, and theglass plate 504 are laminated is obtained. The bonding layer 514 of thefirst intermediate member 517 has a first surface 514 a and a secondsurface 514 b, and at least a part of the conductive heat-generatingbody 516 is embedded in the first surface 514 a of the bonding layer514. In the illustrated example, the conductive heat-generating body 516is completely embedded in the bonding layer 514 from the side of thefirst surface 514 a of the bonding layer 514. As a result, the bondinglayer 514 is in surface contact with the peeling layer 515 via a gapbetween the conductive heat-generating bodies 516. Furthermore, thebonding layer 514 is in surface contact with the entire peeling layer515 exposed in the heat-generating body row 533.

In the examples illustrated in FIGS. 66 to 70, for simple illustration,the flat glass plates 503 and 504 are illustrated. However, actually,the glass plates are curved as in FIG. 63. Since the first intermediatemember 517 is bonded to the glass plate 504, the first intermediatemember 517 is curved in correspondence with the shape of the glass plate504.

Next, as illustrated in FIG. 67, the transparent base material 511 ofthe heating element sheet 512 of the first intermediate member 517 isremoved to produce a second intermediate member 518 (intermediate memberfor laminated glass). In the example illustrated in FIG. 67, thetransparent base material 511 of the heating element sheet 512 is peeledoff from the first intermediate member 517 using the peeling layer 515and is removed from the first intermediate member 517. In a case wherean interface peeling type peeling layer 515 having a layer withrelatively low adhesion with the bonding layer 514 and the conductiveheat-generating body 516 than the adhesion with the transparent basematerial 511 is used as a peeling layer 515, the peeling layer 515 ispeeled off from the bonding layer 514 and the conductive heat-generatingbody 516. In this case, it is possible that the peeling layer 515 doesnot remain on the side of the bonding layer 514 and the conductiveheat-generating body 516. That is, the transparent base material 511together with the peeling layer 515 are removed from the firstintermediate member 517. In the first intermediate member 517 from whichthe transparent base material 511 and the peeling layer 515 are removedin this way, the bonding layer 514 is exposed in the gap between theconductive heat-generating bodies 516.

On the other hand, in a case where an interface peeling type peelinglayer 515 having relatively low adhesion with the transparent basematerial 511 than the adhesion with the bonding layer 514 and theconductive heat-generating body 516 is used as a peeling layer 515, thepeeling layer 515 and the transparent base material 511 are peeled offfrom each other. In a case where an interlayer peeling type peelinglayer 515 that includes a plurality of layers of films and hasrelatively lower adhesion between the plurality of layers than theadhesion with the bonding layer 514, the conductive heat-generating body516, and the transparent base material 511 is used as a peeling layer515, the plurality of layers is peeled off from each other. On the otherhand, an aggregation peeling type peeling layer 515 in which a filler asa dispersed phase is dispersed in a base resin as a continuous phase isused as a peeling layer 515, peeling phenomenon due to cohesive failurein the peeling layer 515 occurs.

The bonding layer 514 of the second intermediate member 518 has a firstsurface 514 a and a second surface 514 b, and at least a part of theconductive heat-generating body 516 is embedded in the first surface 514a of the bonding layer 514.

A laminated glass 510 manufactured as described above is illustrated inFIG. 68. The laminated glass 510 includes the pair of glass plates 503and 504, the bonding layer 514 arranged between the pair of glass plates503 and 504 and bonding the pair of glass plates 503 and 504 to eachother, and the conductive heat-generating bodies 516 arranged betweenthe bonding layer 514 and one of the pair of glass plates 503 and 504.The laminated glass 510 can be manufactured using the heating elementsheet 512 as described above. The conductive heat-generating body 516 ofthe heating element sheet 512 can be produced on the transparent basematerial 511 by using various materials and various methods, and inaddition, a desired pattern can be applied with high accuracy.Therefore, it is possible to reduce adverse effects on visibility causedby light diffusion and light diffraction in the wavy line conductor 508included in the conductive heat-generating body 516. In addition, sincethe conductive heat-generating body 516 has contact with one of the pairof glass plates 503 and 504, a heating efficiency of the glass plates503 and 504 by the conductive heat-generating body 516 can be increased.In addition, the number of interfaces in the laminated glass 510 can bereduced, and the thickness of the entire laminated glass 510 can bereduced. Therefore, deterioration in optical characteristics, that is,deterioration in visibility can be prevented. In addition, the weight ofthe entire laminated glass 510 can be reduced, and this contributes toimprove fuel consumption of a vehicle.

Furthermore, the illustrated heating element sheet 512 is in surfacecontact with the glass plates 503 and 504. In such a laminated glass510, a heating efficiency of the glass plate by the heating elementsheet 512 can be more increased.

Furthermore, in the laminated glass 510 in FIG. 68, since thetransparent base material 511 does not exist between the curved glassplates 503 and 504 and the heating element sheet 512, even when the pairof glass plates 503 and 504 are curved, the bonding layer 514 and theconductive heat-generating body 516 are easily curved in correspondingwith the curve of the glass plates 503 and 504. That is, a disadvantagesuch that the transparent base material 511 causes wrinkles between thepair of glass plates 503 and 504 can be eliminated.

Furthermore, a manufacturing method illustrated in FIGS. 66 to 68includes a process for bonding the glass plate 504 to the heatingelement sheet 512 including the transparent base material 511, thepeeling layer 515 provided on the transparent base material 511, and theconductive heat-generating body 516 provided on the peeling layer 515from the side of the conductive heat-generating body 516 via the bondinglayer 514, a process for removing the transparent base material 511, anda process for bonding the other glass plate 503 to the bonding layer 514from a side opposite to the side facing to the glass plate 504. In thisexample, since the bonding layer 514 and the conductive heat-generatingbody 516 are held by the glass plate 504 when the transparent basematerial 511 is peeled off from the first intermediate member 517, thetransparent base material 511 is easily peeled off. Furthermore, sincethe bonding layer 514 and the glass plate 504 are bonded to the heatingelement sheet 512 at a time, there is an advantage such that the numberof processes can be reduced.

As described above, in a case where an interface peeling type peelinglayer 515 having relatively low adhesion with the transparent basematerial 511 than the adhesion with the bonding layer 514 and theheating element sheet 512 is used as a peeling layer 515, the peelinglayer 515 and the transparent base material 511 are peeled off from eachother. In a case where an interlayer peeling type peeling layer thatincludes a plurality of layers of films and has relatively low adhesionbetween the plurality of layers than the adhesion with the bonding layer514, the heating element sheet 512, and the transparent base material511 is used as a peeling layer 515, the plurality of layers is peeledoff from each other. In a case where an aggregation peeling type peelinglayer in which a filler as a dispersed phase is dispersed in a baseresin as a continuous phase is used as the peeling layer 515, peelingdue to cohesive failure in the peeling layer 515 occurs. In a case wherethese peeling layers 515 are used, in the second intermediate member 518from which the transparent base material 511 is removed by using thepeeling layer 515, at least a part of the peeling layer 515 remains onthe side of the bonding layer 514 and the heating element sheet 512.Therefore, a state where the bonding layer 514 is not exposed in the gapbetween the wavy line conductors 508 occurs. In this case, when theglass plate 503 is laminated on the second intermediate member 518, itis preferable to further provide the bonding layer 513 between thesecond intermediate member 518 and the glass plate 503 to reliably bondthe glass plate 503. In this case, the peeling layer 515 remained on theside of the bonding layer 514 and the heating element sheet 512 is asupporting layer 519 for supporting the heating element sheet 512. Asillustrated in FIG. 69, the laminated glass 510 obtained as a result ofthe above includes the pair of glass plates 503 and 504, the pair ofbonding layers 514 and 513 arranged between the pair of glass plates 503and 504, the supporting layer 519 arranged between the pair of bondinglayers 514 and 513, and the heating element sheet 512 arranged betweenone of the pair of bonding layers 514 and 513 and the supporting layer519 and supported by the supporting layer 519.

In this way, in the present embodiment, a ratio obtained by dividing thetotal length of each curved heat-generating body 532 of the conductiveheat-generating body 516 in the second direction y by the shortestdistance between both ends of each curved heat-generating body 532 isset to be larger than 1.0 and equal to or less than 1.5. With thissetting, uneven heat can be surely prevented within the range of theheat-generating body row 533 including the plurality of curvedheat-generating bodies 532.

Furthermore, in the present embodiment, since the period and theamplitude of the plurality of periodic curved lines included in eachcurved heat-generating body 532 are irregular for each period, a beam oflight and flicker are not conspicuous. Furthermore, since the startposition coordinates of the curved heat-generating bodies 532 in thesecond direction y are irregularly shifted from each other, even whenthe plurality of heat-generating body rows 533 including the pluralityof curved heat-generating bodies 532 is aligned, a beam of light andflicker are inconspicuous.

Aspects of the present invention are not limited to the aboveembodiments and include various modifications that can be conceived bythose skilled in the art, and the effects of the present invention isnot limited to the contents described above. In other words, variousadditions, modifications, and partial deletion can be made withoutdeparting from the conceptual idea and the gist of the present inventionderived from the contents defined in the claims and equivalents thereof.

Seventh Embodiment

Here, “bonding” includes not only “complete bonding” in which bonding iscompleted but also so-called “temporarily bonding” for temporarilybonding before “complete bonding”.

FIGS. 70 and 71 are views for explaining one embodiment of the presentinvention. FIG. 70 is a view schematically illustrating an automobileincluding a heat-generating plate, FIG. 71 is a view of theheat-generating plate viewed from the normal direction of the platesurface, and FIG. 72 is a cross-sectional view of the heat-generatingplate in FIG. 71. Note that the heat-generating plate according to thepresent embodiment may be referred to as a laminated glass.

As illustrated in FIG. 70, an automobile 601 as an example of a vehicleincludes a window glass such as a front window, a rear window, and aside window. Here, a front window 605 configured by a heat-generatingplate 610 is exemplified. In addition, the automobile 601 includes apower supply 607 such as a battery.

The heat-generating plate 610 viewed from a normal direction of a platesurface is illustrated in FIG. 71. A cross-sectional view of theheat-generating plate 610 corresponding to a line LXXII-LXXII in FIG. 71is illustrated in FIG. 72. In the example illustrated in FIG. 72, theheat-generating plate 610 includes a pair of glass plates 611 and 612, aconductive pattern sheet (pattern sheet) 620 arranged between the pairof glass plates 611 and 612, and bonding layers 613 and 614 forrespectively bonding the glass plates 611 and 612 to the conductivepattern sheet 620. In the examples illustrated in FIGS. 70 and 71, theheat-generating plate 610 is curved. However, in FIGS. 72 and 82 to 89,for simple illustration and easy understanding, the heat-generatingplate 610 and the glass plates 611 and 612 having plate-like shapes areillustrated.

The conductive pattern sheet 620 includes a sheet-like base material630, a conductive pattern 640 formed on the base material 630, a wiringportion 615 for energizing the conductive pattern 640, and a connectingportion 616 for connecting the conductive pattern 640 to the wiringportion 615.

In the examples illustrated in FIGS. 71 and 72, the power supply 607such as a battery including a lead storage battery and a lithium ionstorage battery, a solar battery, and a commercial AC power supplysupplies power to the conductive pattern 640 via the wiring portion 615and the connecting portion 616 and heats the conductive pattern 640 byresistance heating. Heat generated by the conductive pattern 640 istransmitted to the glass plates 611 and 612 via the bonding layers 613and 614 and heats the glass plates 611 and 612. As a result, fogging dueto dew condensation attached on the glass plates 611 and 612 can beremoved. In a case where snow or ice is attached on the glass plates 611and 612, snow and ice can be melted. Therefore, a passenger's visibilityis preferably secured.

Particularly, when the glass plates 611 and 612 are used for the frontwindow of an automobile, it is preferable to use a glass with a highvisible light transmittance so as not to interfere the field of view ofa passenger. As a material of the glass plates 611 and 612, soda-limeglass and blue plate glass can be used. It is preferable that atransmittance of the glass plates 611 and 612 in a visible light regionbe equal to or higher than 90%. Here, the visible light transmittance ofthe glass plates 611 and 612 is specified as an average value oftransmittances in respective wavelengths when the transmittance ismeasured by a spectrophotometer (“UV-3100PC” manufactured by SHIMADZUCORPORATION, conforming to JIS K 0115) within a measurement wavelengthrange of 380 nm to 780 nm. The visible light transmittance may belowered by coloring a part of or all of the glass plates 611 and 612. Inthis case, direct sunlight can be shielded, and it is possible to makeit difficult to visually recognize an interior of the vehicle from theoutside of the vehicle.

Furthermore, it is preferable that the glass plates 611 and 612 have athickness of equal to or more than 1 mm and equal to or less than 5 mm.With such a thickness, the glass plates 611 and 612 having excellentstrength and optical characteristics can be obtained.

The glass plates 611 and 612 and the conductive pattern sheet 620 arebonded to each other via the respective bonding layers 613 and 614. Assuch bonding layers 613 and 614, a layer formed of a material havingvarious adhesiveness and viscosity can be used. Furthermore, it ispreferable to use a material having a high visible light transmittancefor the bonding layers 613 and 614. As a typical bonding layer, a layerformed of polyvinyl butyral (PVB) can be exemplified. It is preferablethat the thickness of each of the bonding layers 613 and 614 be equal toor more than 0.15 mm and equal to or less than 0.7 mm.

The heat-generating plate 610 is not limited to the illustrated example,and other function layer that is expected to perform a specific functionmay be provided. Furthermore, one functional layer may perform two ormore functions, and for example, a function may be applied to at leastone of the glass plates 611 and 612 and the bonding layers 613 and 614of the heat-generating plate 610 and the base material 630 of theconductive pattern sheet 620 to be described later. As an example of thefunction that can be applied to the heat-generating plate 610, ananti-reflection (AR) function, a hard coating (HC) function havingscratch resistance, an infrared ray shielding (reflection) function, anultraviolet ray shielding (reflection) function, a polarizationfunction, and an antifouling function can be exemplified.

Next, the conductive pattern sheet 620 will be described. The conductivepattern sheet 620 includes a sheet-like base material 630, a conductivepattern 640 provided on the base material 630, a wiring portion 615 forenergizing the conductive pattern 640, and a connecting portion 616 forconnecting the conductive pattern 640 to the wiring portion 615. Theconductive pattern 640 is formed by arranging conductive thin wires,formed of metals and the like, in a predetermined pattern. Theconductive pattern sheet 620 may have substantially the same planerdimensions as the glass plates 611 and 612 and be arranged across theentire heat-generating plate 610 and may be arranged on a part of theheat-generating plate 610 such as a front portion of a driver's seat.

The sheet-like base material 630 functions as a base material forsupporting the conductive pattern 640. The base material 630 is aso-called transparent electrically insulating substrate for transmittinglight with a wavelength in a visible light wavelength band (380 nm to780 nm).

Although the resin included in the base material 630 may be any resin aslong as the resin transmits visible light, a thermoplastic resin can bepreferably used. As a thermoplastic resin, for example, an acrylic resinsuch as polymethyl methacrylate, a polyester resin such as polyvinylchloride, polyethylene terephthalate, and amorphous polyethyleneterephthalate (A-PET), a polyethylene resin, a polyolefin resin such aspolypropylene, a cellulose resin such as triacetylcellulose (cellulosetriacetate), polystyrene, a polycarbonate resin, and an AS resin can beexemplified. In particular, an acrylic resin and polyvinyl chloride arepreferable since an acrylic resin and polyvinyl chloride are excellentin etching resistance, weather resistance property, and light resistanceproperty.

In consideration of retention and a light transmittance of theconductive pattern 640, it is preferable that the thickness of the basematerial 630 be equal to or more than 0.03 mm and equal to or less than0.3 mm.

With reference to FIGS. 73 to 75, the conductive pattern 640 will bedescribed. The conductive pattern 640 is energized from the power supply607 such as a battery via the wiring portion 615 and the connectingportion 616 and generates heat by resistance heating. Then, the heat istransmitted to the glass plates 611 and 612 via the bonding layers 613and 614 so as to heat the glass plates 611 and 612.

Regarding the conductive pattern 640 according to the presentembodiment, a reference pattern 650 is determined which includes aplurality of line segments 654 extending between two branch points 652and defining an opening region 653, and subsequently, positions ofbranch points 642 of the conductive pattern 640 are determined based onthe branch points 652 of the reference pattern 650, and after that,positions of connection elements 644 of the conductive pattern 640 aredetermined based on the determined branch points 642 of the conductivepattern 640 and the line segments 654 of the reference pattern 650.

FIG. 73 is a plan view illustrating the reference pattern 650. Asillustrated in FIG. 73, the reference pattern 650 is a mesh patterndefining a large number of opening regions 653. The reference pattern650 includes the plurality of line segments 654 extending between thetwo branch points 652 and defining the opening region 653. That is, thereference pattern 650 is formed as a group of a large number of linesegments 654 having the branch points 652 formed at both ends.

In the example illustrated in FIG. 73, a large number of opening regions653 of the reference pattern 650 are arranged with a shape and a pitchhaving no repeating regularity (periodic regularity). In particular, inthe illustrated example, a large number of opening regions 653 arearranged so as to coincide with Voronoi regions in the Voronoi diagramgenerated from virtual points, that is, sites in which distances betweenadjacent points are randomly distributed between a predetermined upperlimit and a predetermined lower limit in a planar view. In other words,each line segment 654 of the reference pattern 650 coincides with eachboundary between the Voronoi regions in the Voronoi diagram. Inaddition, each branch point 652 of the reference pattern 650 coincideswith a Voronoi point in the Voronoi diagram.

The Voronoi diagram can be obtained by a known method as disclosed in,for example, JP 2012-178556 A, JP 2011-216378 A, and JP 2012-151116 A.Therefore, detailed description on a method for creating the Voronoidiagram will be omitted.

FIG. 74 illustrates an enlarged view of a part of the conductive pattern640 with the reference pattern 650 illustrated in FIG. 73. First, eachbranch point 642 of the conductive pattern 640 is arranged on eachbranch point 652 of the reference pattern 650. Next, each connectionelement 644 of the conductive pattern 640 is arranged to connect betweenthe two branch points 642 respectively corresponding to the two branchpoints 652 that are both ends of the line segment 654 of the referencepattern 650. Each connection element 644 may be a straight line segmentwhich is a part of a straight line, a curved line segment which is apart of a curved line, or a combination thereof. For example, eachconnection element 644 may have a shape of a straight line segment, apolygonal line, a curved line segment, or the like. Here, less than 20%of the plurality of connection elements 644 is the connection elements644 for connecting the two branch points 642 as a straight line segment.That is, equal to or more than 80% of the plurality of connectionelements 644 have a shape of a polygonal line or a curved line segmentother than a straight line segment. A curved line forming the curvedline segment is not particularly limited. For example, the curved linecan be appropriately selected from among a circle, an ellipse, acardioid, a sinusoidal curve, a Jacobi elliptic functional curve, ahyperbolic sine function curve, a Bessel function curve, an involutecurve, a function curve of degree of n (n is an integral of two or more)other than a circle and an ellipse.

In the example illustrated in FIG. 74, the conductive pattern 640includes the plurality of branch points 642 arranged on each branchpoint 652 of the reference pattern 650, and the plurality of connectionelements 644 extending between the two branch points 642 and definingthe opening region 643, and the connection elements 644 for connectingtwo branch points 642 as a straight line segment are less than 20% ofthe plurality of connection elements 644. The conductive pattern 640 hasa mesh pattern in which the connection elements 644 are arranged incorrespondence with the respective line segments 654 of the referencepattern 650.

It is not necessary to calculate and specify the ratio of the connectionelements 644 for connecting between the two branch points 642 as astraight line segment relative to the plurality of connection elements644 by examining the entire region of the conductive pattern 640. Inactual, in one section having an area expected to reflect overalltendencies of the ratio of the connection elements 644 for connectingthe two branch points 642 as a straight line segment relative to theplurality of connection elements 644, the ratio can be calculated andspecified by examining an appropriate number of targets in considerationof variation in the numbers to be examined. The value specified in thisway can be used as a ratio of the connection elements 644 for connectingthe two branch points 642 as a straight line segment relative to theplurality of connection elements 644. In the conductive pattern 640according to the present embodiment, by observing 100 points included ina region of 300 mm×300 mm by an optical microscope or an electronmicroscope, the ratio of the connection elements 644 for connecting twobranch points 642 as a straight line segment relative to the pluralityof connection elements 644 can be specified.

As a material of such a conductive pattern 640, for example, one or moreof gold, silver, copper, platinum, aluminum, chromium, molybdenum,nickel, titanium, palladium, indium, tungsten, and an alloy thereof canbe exemplified.

In the example illustrated in FIG. 72, the connection element 644includes a surface 644 a on the side of the base material 630, a surface644 b opposite to the base material 630, and side surfaces 644 c and 644d, and has a substantially rectangular cross section as a whole. It ispreferable that a width W of the connection element 644, that is, awidth W of the base material 630 along the sheet surface be equal to ormore than 1 μm and equal to or less than 15 μm. It is preferable thatthe width W of the base material 630 along the sheet surface be equal toor more than 1 μm and equal to or less than 7 μm. According to theconnection element 644 having such a width W, since the connectionelement 644 is sufficiently thinned, the conductive pattern 640 can beeffectively made invisible. In addition, since a sufficient width W ofthe connection element 644, that is, mechanical strength and an electricconductivity (reciprocal of electric resistance) are ensured, theconnection element 644 is hardly disconnected during a manufacturingprocess and during usage of the connection element 644 as aheat-generating plate, and a sufficient heating value can be secured. Inaddition, it is preferable that a height (thickness) H of the connectionelement 644, that is, the height (thickness) H along the normaldirection to the sheet surface of the base material 630 be equal to ormore than 1 μm and equal to or less than 20 μm. In addition, it is morepreferable that the height H of the connection element 644 be equal toor more than 2 μm and equal to or less than 14 μm. The height(thickness) H of the connection element 644 can be the height(thickness) of the conductive pattern 640. According to the connectionelement 644 having such a height (thickness) H, sufficient conductivitycan be secured while having an appropriate resistance value.

According to the conductive pattern 640 as described above, asillustrated in FIG. 75, light entering the side surface of theconnection element 644 having the shape of a curved line segment, apolygonal line, and the like other than a straight line segment isdiffusely reflected by the side surface. As a result, the light enteringthe side surface of the connection element 644 from a certain directioncan be prevented from being reflected by the side surface in a certaindirection in correspondence with the incident direction. Therefore, itis possible to prevent that the reflected light is observed by anobserver and the conductive pattern 640 having the connection element644 is visually recognized by the observer. In particular, in a casewhere the connection elements 644 for connecting between the two branchpoints 642 as a straight line segment are less than 20% of the pluralityof connection elements 644, that is, in a case where more than 80% ofthe plurality of connection elements 644 have shapes such as a curvedline segment or a polygonal line other than a straight line segment, itcan be more effectively prevented that the light reflected by the sidesurface of the connection element 644 is visually recognized by theobserver and the conductive pattern 640 including the connection element644 is visually recognized by the observer.

In a case where the height (thickness) H of the connection element 644is equal to or more than 1 μm, in particular, in a case where the heightH of the connection element 644 is equal to or more than 2 μm, apossibility such that the light reflected by the side surface of theconnection element 644 is observed by the observer is increased.Therefore, in this case, to prevent that the light reflected by the sidesurface of the connection element 644 is visually recognized by theobserver, it is especially more effective that the connection elementsfor connecting the two branch points 642 as a straight line segment areless than 20% of the plurality of connection elements 644.

In addition, when the distribution of the opening regions 643 is coarseand an average distance D_(ave) between median points of the twoadjacent opening regions 643 becomes longer, each connection element 644is lengthened. When each connection element 644 is lengthened, the lightreflected by the side surface of the connection element 644 in apredetermined direction is easily and visually recognized. As a resultof examination by the inventors of the present invention, in a casewhere the average distance D_(ave) between the median points of the twoadjacent opening regions 643 is equal to or longer than 50 μm, andespecially, in a case where the average distance D_(ave) is equal to orlonger than 70 μm, the light reflected by the side surface of theconnection element 644 is visually recognized by the observer with highpossibility. Therefore, in this case, to prevent that the lightreflected by the side surface of the connection element 644 is visuallyrecognized by the observer, it is especially more effective that theconnection elements for connecting the two branch points 642 as astraight line segment are less than 20% of the plurality of connectionelements 644. Here, the two adjacent opening regions 643 are twoadjacent opening regions 643 that share a single connection element 644.As illustrated in FIG. 75, a distance D between median points G₁ and G₂is a linear distance D between the median points G₁ and G₂.

It is preferable that the average distance D_(ave) between the medianpoints of the two adjacent opening regions 643 of the conductive pattern640 be equal to or shorter than 800 μm. When the distance D_(ave) isequal to or shorter than 800 μm, the conductive pattern 640 can beeffectively made invisible. When the distance D_(ave) is equal to orshorter than 300 μm, the conductive pattern 640 can be more effectivelymade invisible. It is considered that human eyes hardly separate andresolve the opening region 643 of the conductive pattern 640 with such asmall D_(ave) from the adjacent opening region 643. On the other hand,it is preferable that the distance D_(ave) be equal to or longer than 50μm. When the distance D_(ave) is equal to or longer than 50 μm, anopening rate sufficient for allowing light passing through the regionwhere the conductive pattern 640 is arranged can be ensured, and anexcellent light transmittance can be applied to the conductive pattern640 and the heat-generating plate 610. When the D_(ave) is equal to orlonger than 50 μm, for example, when the width W of the connectionelement is equal to or less than 5 μm, the light transmission rate ofthe heat-generating plate 610 can be equal to or more than 70% as anexample.

In a case where the average distance D_(ave) between the median pointsof the two adjacent opening regions 643 of the conductive pattern 640 isequal to or longer than 50 μm and equal to or shorter than 800 μm, anexcellent light transmittance can be applied to the conductive pattern640 and the heat-generating plate 610, and the conductive pattern 640can be effectively made invisible. In a case where the average distanceD_(ave) between the median points of the two adjacent opening regions643 of the conductive pattern 640 is equal to or longer than 50 μm andequal to or shorter than 800 μm, and especially, in a case where theaverage distance D_(ave) is equal to or longer than 70 μm and equal toor shorter than 800 μm, by setting the connection elements forconnecting two branch points 642 as a straight line segment to be lessthan 20% of the plurality of connection elements 644, it can beeffectively prevented that the light reflected by the side surface ofthe connection element 644 is visually recognized by an observer, andthe conductive pattern 640 can be effectively made invisible.Furthermore, in a case where the average distance D_(ave) between themedian points of the two adjacent opening regions 643 of the conductivepattern 640 is equal to or longer than 50 μm and equal to or shorterthan 300 μm, an excellent light transmittance can be applied to theconductive pattern 640 and the heat-generating plate 610, and theconductive pattern 640 can be more effectively made invisible. Inaddition, in a case where the average distance D_(ave) between themedian points of the two adjacent opening regions 643 of the conductivepattern 640 is equal to or longer than 50 μm and equal to or shorterthan 300 μm, and especially, in a case where the average distanceD_(ave) is equal to or longer than 70 μm and equal to or shorter than800 μm, by setting the connection elements for connecting two branchpoints 642 as a straight line segment to be less than 20% of theplurality of connection elements 644, it can be effectively preventedthat the light reflected by the side surface of the connection element644 is visually recognized by an observer, and the conductive pattern640 can be more effectively made invisible.

In the example illustrated in FIG. 72, the connection element 644includes the first dark color layer 663 provided on the base material630, the conductive metal layer 661 provided on the first dark colorlayer 663, and the second dark color layer 664 provided on theconductive metal layer 661. In other words, a surface of the conductivemetal layer 661 on the side of the base material 630 is covered with thefirst dark color layer 663, and a surface of the conductive metal layer661 opposite to the base material 630 and both side surfaces are coveredwith the second dark color layer 664. It is preferable that the darkcolor layers 663 and 664 be layers having lower reflectance of visiblelight than the conductive metal layer 661, for example, the dark colorlayers 663 and 664 are layers of dark colors such as black. With thedark color layers 663 and 664, the conductive metal layer 661 is hardlyand visually recognized, and a passenger's visibility is more preferablysecured.

Next, an example of a manufacturing method for the heat-generating plate610 will be described with reference to FIGS. 76 to 82. FIGS. 76 to 82are cross-sectional views sequentially illustrating the example of themanufacturing method for the heat-generating plate 610.

First, a sheet-like base material 630 is prepared. The base material 630is a so-called transparent electrically insulating resin base materialfor transmitting light with a wavelength in a visible light wavelengthband (380 nm to 780 nm).

Next, as illustrated in FIG. 76, a first dark color layer 663 isprovided on the base material 630. For example, the first dark colorlayer 663 can be provided on the base material 630 by a plating methodincluding electroplating and electroless plating, a sputtering method, aCVD method, a PVD method, and an ion plating method or a method ofcombination of two or more methods described above. As a material of thefirst dark color layer 663, various known materials can be used. Forexample, copper nitride, copper oxide, copper oxynitride, and nickelnitride can be exemplified.

Next, as illustrated in FIG. 77, a conductive metal layer (conductivelayer) 61 is provided on the first dark color layer 663. As describedabove, the conductive metal layer 661 is a layer formed of one or moreof gold, silver, copper, platinum, aluminum, chromium, molybdenum,nickel, titanium, palladium, indium, tungsten, and alloys thereof. Theconductive metal layer 661 may be formed by a known method. For example,a method of bonding a metal foil such as a copper foil with an adhesivehaving weather resistance property, a plating method includingelectroplating and electroless plating, a sputtering method, a CVDmethod, a PVD method, an ion plating method, or a method of combinationof two or more methods described above can be employed.

In a case where the conductive metal layer 661 is formed of a metal foilsuch as a copper foil, the first dark color layer 663 is formed on onesurface of the metal foil in advance, and the metal foil on which thefirst dark color layer 663 is formed may be laminated on the basematerial 630, for example, via an adhesive layer or a viscosity layer sothat the first dark color layer 663 faces to the base material 630. Inthis case, for example, by performing darkening processing (blackeningprocessing) on a part of the material forming the metal foil, the firstdark color layer 663 formed of metal oxide or metal sulfide can beformed from a part of the material that has formed the metal foilFurthermore, the first dark color layer 663 may be provided on thesurface of the metal foil such as a coating film of a dark colormaterial and a plating layer of nickel or chromium. In addition, thefirst dark color layer 663 may be provided by roughening the surface ofthe metal foil.

Next, as illustrated in FIG. 78, a resist pattern 662 is provided on theconductive metal layer 661. The resist pattern 662 is a patterncorresponding to the pattern of the conductive pattern 640 to be formed.In the method described here, the resist pattern 662 is provided only ona portion finally forming the conductive pattern 640. The resist pattern662 can be formed by patterning using a known photolithographytechnique.

Next, as illustrated in FIG. 79, the conductive metal layer 661 and thefirst dark color layer 663 are etched using the resist pattern 662 as amask. By this etching, the conductive metal layer 661 and the first darkcolor layer 663 are patterned to substantially the same pattern as theresist pattern 662. An etching method is not particularly limited, and aknown method can be employed. As a known method, for example, wetetching using an etchant and plasma etching can be exemplified. Afterthat, as illustrated in FIG. 80, the resist pattern 662 is removed.

Thereafter, as illustrated in FIG. 81, the second dark color layer 664is formed on the surface 644 b of the conductive metal layer 661opposite to the base material 630 and the side surfaces 644 c and 644 d.For example, by performing darkening processing (blackening processing)on a part of the material forming the conductive metal layer 661, thesecond dark color layer 664 formed of metal oxide or metal sulfide canbe formed from a part of the conductive metal layer 661. Furthermore,the second dark color layer 664 may be provided on the surface of theconductive metal layer 661 as a coating film of a dark color materialand a plating layer of nickel or chromium. In addition, the second darkcolor layer 664 may be provided by roughening the surface of theconductive metal layer 661.

As described above, the conductive pattern sheet 620 illustrated in FIG.81 is produced.

Finally, the glass plate 611, the bonding layer 613, the conductivepattern sheet 620, the bonding layer 614, and the glass plate 612 arelaminated in this order and heated and pressurized. In the exampleillustrated in FIG. 82, first, the bonding layer 613 is temporarilybonded to the glass plate 611, and the bonding layer 614 is temporarilybonded to the glass plate 612. Next, the glass plate 611 to which thebonding layer 613 is temporarily bonded, the conductive pattern sheet620, and the glass plate 612 to which the bonding layer 614 istemporarily bonded are laminated in this order and heated andpressurized so that the sides of the glass plates 611 and 612 to whichthe bonding layers 613 and 614 are respectively and temporarily bondedface to the conductive pattern sheet 620. With this structure, the glassplate 611, the conductive pattern sheet 620, and the glass plate 612 arebonded via the bonding layers 613 and 614, and the heat-generating plate610 illustrated in FIG. 72 is manufactured.

The heat-generating plate 610 according to the present embodimentdescribed above includes the pair of glass plates 611 and 612, theconductive pattern 640 arranged between the pair of glass plates 611 and612 and defining the plurality of opening regions 643, and the bondinglayers 613 and 614 arranged between the conductive pattern 640 and atleast one of the pair of glass plates 611 and 612, and the conductivepattern 640 includes the plurality of connection elements 644 extendingbetween the two branch points 642 and defining the opening region 643,and the connection elements for connecting the two branch points 642 asa straight line segment are less than 20% of the plurality of connectionelements 644.

According to such a heat-generating plate 610, as illustrated in FIG.75, light entering the side surface of the connection element 644 havingthe shape of a polygonal line, a curved line segment, and the like otherthan a straight line segment is diffusely reflected by the side surface.As a result, the light entering each point in the side surface of theconnection element 644 from a certain direction can be prevented frombeing reflected by the side surface in a certain direction incorrespondence with the incident direction. Therefore, it is possible toprevent that the reflected light is observed by an observer and theconductive pattern 640 having the connection element 644 is visuallyrecognized by the observer.

Note that various modifications can be made to the embodiment.Hereinafter, modifications will be described as appropriately referringto the drawings. In the following description and the drawings used inthe following description, parts which are similarly formed to those inthe embodiments are denoted with the same reference numerals as thoseused for corresponding parts of the embodiment, and overlappeddescription will be omitted.

A modification of a manufacturing method for a heat-generating plate 610will be described with reference FIGS. 83 to 87. FIGS. 83 to 87 arecross-sectional views sequentially illustrating the modification of themanufacturing method for the heat-generating plate 610.

First, a conductive pattern sheet 620 is produced. The conductivepattern sheet 620 can be manufactured by the method described in theexample of the manufacturing method for the heat-generating plate 610described above.

Next, a glass plate 611, a bonding layer 613, and the conductive patternsheet 620 are laminated in this order and heated and pressurized. In theexample illustrated in FIG. 83, first, the bonding layer 613 istemporarily bonded to the glass plate 611. Next, the glass plate 611 towhich the bonding layer 613 is temporarily bonded is laminated from theside of the conductive pattern sheet 620 of the conductive pattern 640and heated and pressurized so that the side of the glass plate 611 towhich the bonding layer 613 is temporarily bonded faces to theconductive pattern sheet 620. With this structure, as illustrated inFIG. 84, the glass plate 611 and the conductive pattern sheet 620 arebonded to each other (temporarily bonded or completely bonded) via thebonding layer 613.

Next, as illustrated in FIG. 85, a base material 630 of the conductivepattern sheet 620 is removed. For example, when the conductive patternsheet 620 is produced, a peeling layer is formed on the base material630 in advance, and the conductive pattern 640 is formed on the peelinglayer. It is preferable that the peeling layer be not removed in aprocess for etching the conductive metal layer 661 and the first darkcolor layer 663. In this case, the base material 630 is bonded to theconductive pattern 640 and the bonding layer 613 via the peeling layer.Then, in a process for removing the base material 630 of the conductivepattern sheet 620, the base material 630 of the conductive pattern sheet620 is peeled off from the conductive pattern 640 and the bonding layer613 by using the peeling layer.

As a peeling layer, for example, an interface peeling type peelinglayer, an interlayer peeling type peeling layer, and an aggregationpeeling type peeling layer can be used. As an interface peeling typepeeling layer, a peeling layer having relatively lower adhesion with theconductive pattern 640 and the bonding layer 613 than the adhesion withthe base material 630 can be preferably used. As such a layer, asilicone resin layer, a fluororesin layer, and a polyolefin resin layer,and the like can be exemplified. A peeling layer having relatively loweradhesion with the base material 630 than the adhesion with theconductive pattern 640 and the bonding layer 613 can be used. As aninterlayer peeling type peeling layer, a peeling layer including aplurality of layers and having relatively lower adhesion between theplurality of layers than the adhesion with the conductive pattern 640,the bonding layer 613, and the base material 630 can be exemplified. Asan aggregation peeling type peeling layer, a peeling layer in which afiller as a dispersed phase is dispersed in a base resin as a continuousphase can be exemplified.

In a case where an interface peeling type peeling layer havingrelatively lower adhesion with the conductive pattern 640 and thebonding layer 613 than the adhesion with the base material 630 is used,the peeling layer is peeled off from the conductive pattern 640 and thebonding layer 613. In this case, it is possible to prevent the peelinglayer from remaining on the side of the conductive pattern 640 and thebonding layer 613. That is, the base material 630 and the peeling layerare removed. When the base material 630 and the peeling layer areremoved, the bonding layer 613 is exposed in an opening region 643 ofthe conductive pattern 640.

On the other hand, in a case where an interface peeling type peelinglayer having relatively lower adhesion with the base material 630 thanthe adhesion with the conductive pattern 640 and the bonding layer 613is used as a peeling layer, the peeling layer is peeled off from thebase material 630. In a case where an interlayer peeling type peelinglayer including a plurality of layers of films and having relativelylower adhesion between the plurality of layers than the adhesion withthe conductive pattern 640, the bonding layer 613, and the base material630 is used as a peeling layer, the plurality of layers is peeled offfrom each other. In a case where an aggregation peeling type peelinglayer in which a filler as a dispersed phase is dispersed in a baseresin as a continuous phase is used as a peeling layer, peelingphenomenon due to cohesive failure in the peeling layer occurs.

Finally, the glass plate 611, the bonding layer 613, the conductivepattern 640, the bonding layer 614, and the glass plate 612 arelaminated in this order and heated and pressurized. In the exampleillustrated in FIG. 86, first, the bonding layer 614 is temporarilybonded to the glass plate 612. Next, the glass plate 611, the conductivepattern 640, the bonding layer 613, and the glass plate 612 to which thebonding layer 614 is temporarily bonded are laminated in this order andheated and pressurized so that the side of the glass plate 612 to whichthe bonding layer 614 is temporarily bonded faces to the conductivepattern 640 and the bonding layer 613. With this structure, the glassplate 611, the conductive pattern 640, and the glass plate 612 arebonded (completely bonded) via the bonding layers 613 and 614, and theheat-generating plate 610 illustrated in FIG. 87 is manufactured.

According to the heat-generating plate 610 illustrated in FIG. 87, it ispossible that the heat-generating plate 610 does not include the basematerial 630. With this structure, the thickness of the entireheat-generating plate 610 can be reduced. In addition, the number ofinterfaces in the heat-generating plate 610 can be reduced. Therefore,deterioration in optical characteristics, that is, deterioration invisibility can be prevented.

Next, another modification of a manufacturing method for theheat-generating plate 610 will be described with reference to FIGS. 88and 89. FIGS. 88 and 89 are cross-sectional views sequentiallyillustrating another modification of the manufacturing method for theheat-generating plate 610.

First, according to a process similar to that in the modification of themanufacturing method for the heat-generating plate 610, a structure inwhich a glass plate 611 and a conductive pattern sheet 620 are bonded(temporarily bonded) via a bonding layer 613 is produced, and a basematerial 630 is removed from the structure. That is, a laminate, inwhich the glass plate 611, the conductive pattern 640, and the bondinglayer 613 are laminated, described in the modification of themanufacturing method for the heat-generating plate 610 with reference toFIG. 85 is obtained.

Next, as illustrated in FIG. 88, the glass plate 611, the bonding layer613, the conductive pattern 640, and the glass plate 612 are laminatedin this order and heated and pressurized. As a result, the glass plate611 is bonded (completely bonded) to the conductive pattern 640 via thebonding layer 613, and the glass plate 611 is bonded (completely bonded)to the glass plate 612 via the bonding layer 613. Then, theheat-generating plate 610 illustrated in FIG. 89 is manufactured.

According to the heat-generating plate 610 illustrated in FIG. 89, it ispossible that the heat-generating plate 610 does not include the basematerial 630 and the bonding layer 614. With this structure, thethickness of the entire heat-generating plate 610 can be more reduced.In addition, the number of interfaces in the heat-generating plate 610can be more reduced. Therefore, deterioration in opticalcharacteristics, that is, deterioration in visibility can be moreeffectively prevented. In addition, since the conductive pattern 640 hascontact with the glass plate 612, a heating efficiency of the glassplate 612 by the conductive pattern 640 can be enhanced.

As another modification, FIG. 90 illustrates a modification of areference pattern. As illustrated in FIG. 90, a reference pattern 750 isa mesh pattern defining a large number of opening regions 753. Thereference pattern 750 includes a plurality of line segments 754extending between the two branch points 752 and defining the openingregions 753. That is, the reference pattern 750 is formed as a group ofa large number of line segments 754 forming the branch points 752 atboth ends. Especially, in the illustrated example, the reference pattern750 has a shape obtained by extending the reference pattern 650illustrated in FIG. 73 along a first direction (X), in other words, ashape obtained by compressing the reference pattern 650 illustrated inFIG. 73 along a second direction (Y) perpendicular to the firstdirection (X).

A part of the conductive pattern 740 determined by the method describedwith reference to FIG. 74 based on the reference pattern 750 is enlargedand illustrated in FIG. 91 together with a part of the correspondingreference pattern 750. In the example illustrated in FIG. 91, theconductive pattern 740 includes the plurality of branch points 742arranged on each branch point 752 of the reference pattern 750, and theplurality of connection elements 744 extending between the two branchpoints 742 and defining the opening region 743, and the connectionelements for connecting two branch points 742 as straight line segmentsare less than 20% of the plurality of connection elements 744. Theconductive pattern 740 has a mesh pattern in which the connectionelements 744 are arranged in correspondence with the respective linesegments 754 of the reference pattern 750.

In the example illustrated in FIG. 91, an average of a ratio (L₁/L₂) ofa length L₁ of each opening region 743 of the conductive pattern 740along the first direction (X) relative to a length L₂ of the openingregion 743 along the second direction (Y) perpendicular to the firstdirection (X) is equal to or more than 1.3 and equal to or less than1.8. In a case where the conductive pattern 740 includes the openingregion 743 having such a size, a possibility such that light reflectedby the side surface of the connection element 744 is visually recognizedby an observer is increased. Therefore, in this case, to prevent thatthe light reflected by the side surface of the connection element 744 isvisually recognized by the observer, it is especially more effectivethat the connection elements for connecting the two branch points 742 asa straight line segment are less than 20% of the plurality of connectionelements 744.

Each size of the conductive patterns 640 and 740 such as the averagedistance D_(ave) between the median points of the two adjacent openingregions 643 and the average of the ratio (L₁/L₂) of the length L₁ ofeach opening region 743 of the conductive pattern 740 along the firstdirection (X) relative to the length L₂ of the opening region 743 alongthe second direction (Y) perpendicular to the first direction (X) arenot necessarily specified by examining the entire regions of theconductive patterns 640 and 740 and calculating average values. Inactual, in a single section having an area which is expected to reflectoverall tendencies of values to be examined (the average distanceD_(ave) between the median points of the two adjacent opening regions643 and the average of the ratio (L₁/L₂) of the length L₁ of eachopening region 743 of the conductive pattern 740 along the firstdirection (X) relative to the length L₂ of the opening region 743 alongthe second direction (Y) perpendicular to the first direction (X)), eachsize can be calculated and specified by examining an appropriate numberof targets in consideration of variation in the numbers to be examined.The values specified in this way are respectively used as the averagedistance D_(ave) between the median points of the two adjacent openingregions 643 and the average of the ratio (L₁/L₂) of the length L₁ ofeach opening region 743 of the conductive pattern 740 along the firstdirection (X) relative to the length L₂ of the opening region 743 alongthe second direction (Y) perpendicular to the first direction (X). Inthe conductive patterns 640 and 740 according to the present embodiment,by measuring 100 points included in the region of 300 mm×300 mm by anoptical microscope or an electron microscope and calculating an average,the sizes of the conductive patterns 640 and 740 can be specified.

As another modification, in the embodiment described above, theconductive patterns 640 and 740 have a pattern determined based on theVoronoi diagram generated from sites randomly distributed in a planarsurface, that is, in which a large number of opening regions 653 and 753are arranged with shapes and pitches with no repeating regularity(periodic regularity). However, the pattern is not limited to this, andpatterns such as a pattern in which opening regions having the sameshapes such as a triangle, a rectangle, and a hexagon are regularlyarranged, a pattern in which opening region having different shapes areregularly arranged may be used.

In the examples illustrated in FIGS. 76 to 89, the second dark colorlayer 664 forms the surface 644 b opposite to the base material 630 ofthe connection element 644 and the side surfaces 644 c and 644 d.However, the modification is not limited to this, and the second darkcolor layer 664 may form only the surface 644 b opposite to the basematerial 630 of the connection element 644 or only the side surfaces 644c and 644 d of the connection element 644. In a case where the seconddark color layer 664 forms only the surface 644 b opposite to the basematerial 630 of the connection element 644, for example, after theprocess illustrated in FIG. 77, the second dark color layer 664 and theresist pattern 662 are provided on the conductive metal layer(conductive layer) 661 in this order. Thereafter, it is preferable thatthe second dark color layer 664, the conductive metal layer 661, and thefirst dark color layer 663 be etched by using the resist pattern 662 asa mask. In a case where the second dark color layer 664 forms only theside surfaces 644 c and 644 d of the connection element 644, forexample, after the process illustrated in FIG. 79, the second dark colorlayer 664 is formed without removing the resist pattern 662, and theresist pattern 662 may be removed after that. In a case where it is notnecessary to provide the first dark color layer 663, the process forproviding the first dark color layer 663 on the base material 630illustrated in FIG. 76 may be omitted.

The heat-generating plate 610 may be used for a rear window, a sidewindow, or a sunroof of an automobile 601. In addition, theheat-generating plate 610 may be used for a window or a door of avehicle, such as a railway vehicle, an aircraft, a ship, and aspacecraft, other than an automobile.

In addition to vehicles, the heat-generating plate 610 can be used for awindow or a door of a building such as a shop and a house, especially ina place where indoor and outdoor is divided, a window material (cover orprotection glass plate) of various traffic lights, a window material ofa headlamp of various vehicles, and the like.

Although some modifications regarding the embodiment have been describedabove, naturally, a plurality of modifications can be appropriatelycombined and applied.

EXAMPLES

Hereinafter, although the present invention will be described in moredetail with reference to examples, the present invention is not limitedto the examples.

Example 4

A laminated glass in Example 4 is produced as follows. First, as a basematerial 630, a biaxially stretched polyethylene terephthalate (PET)film (manufactured by TOYOBO CO., LTD. A4300) with the thickness of 100μm, the width of 98 cm, and the length of 100 m is prepared. Atwo-liquid mixed curable type urethane ester type adhesive is laminatedon the base material 630 by a gravure coater so that a dried thicknessof the laminate at the time when the laminate is cured is 7 μm. Then, anelectrolytic copper foil with the thickness of 3 μm, the width of 97 cm,and the length of 80 m is laminated as the conductive metal layer 661 onthe base material 630 via adhesive, and this state is maintained forfour days under an environment with an ambient temperature of 50° C.,and the electrolytic copper foil is fixed to the base material 630.

Thereafter, a layer of a photosensitivity resist material is laminatedon the electrolytic copper foil (conductive metal layer 661) with amercury lamp via a photomask having a pattern including the plurality ofconnection elements determined based on the reference pattern 650 havinga large number of opening regions 653 arranged so as to coincide withthe Voronoi regions in the Voronoi diagram generated from the sites ofwhich the distance between the adjacent sites are randomly distributedbetween the predetermined upper limit and the predetermined lower limitin the planar surface described with reference to FIGS. 73 and 74. Then,the resist pattern 662 is formed by cleaning (removing) an extraphotosensitivity resist material, and the electrolytic copper foil isetched by using corrosive liquid of aqueous ferric chloride solutionusing the resist pattern 662 as a mask. Then, the resist pattern 662 iscleaned with pure water and the remaining resist pattern 662 is removedso as to obtain the conductive pattern sheet 620 having the conductivepattern 640 including the plurality of connection elements 644determined based on the reference pattern 650 having a large number ofopening regions 653 arranged so as to coincide with the Voronoi regionsin the Voronoi diagram. In the conductive pattern sheet 620, the width Wof the connection element 644 of the conductive pattern 640 is 7 μm, andthe height (thickness) of the connection element 644, that is, theheight (thickness) H of the conductive pattern 640 is 3 μm. The ratio ofthe connection elements 644 for connecting the two branch points 642 ofthe conductive pattern 640 as a straight line segment relative to theall of the connection elements 644 is 15%. The average distance D_(ave)between the median points of the two adjacent opening regions 643 of theconductive pattern 640 is 50 μm. The ratio of the connection elements644 for connecting the two branch points 642 of the conductive pattern640 as a straight line segment relative to all the connection elements644 is specified by observing 100 points in the region of 300 mm×300 mmin the conductive pattern 640 with an optical microscope.

Then, the conductive pattern sheet 620 obtained as described above iscut into a substantially trapezoidal shape having an upper base of 125cm, a bottom base of 155 cm, and a height of 96 cm. Then, the conductivepattern sheet 620 is arranged between the substantially trapezoidalglass plates 611 and 612 having the shape and the size with the upperbase of 120 cm, and the lower base of 150 cm, and the height of 95 cm ina case of being observed from the normal direction of the surfaces (pairof surface having the largest area) via the bonding layers 613 and 614including a PVB adhesive sheet having the same as the glass plates 611and 612. Then, the laminate is heated and pressurized (vacuumlamination). Then, the bonding layers 613 and 614 and the conductivepattern sheet 620 protruding from the peripheries of the glass plates611 and 612 are trimmed, and the heat-generating plate 610 in Example 4is obtained.

When the heat-generating plate 610 according to Example 4 is visuallychecked, the conductive pattern 640 is not visually recognized at adistance of 60 cm from the heat-generating plate 610. Furthermore, theconductive pattern 640 cannot be visually recognized at a distance equalto or more than 60 cm. As a result, it can be confirmed that theconductive pattern 640 of the heat-generating plate 610 according toExample 4 is sufficiently invisible. A light transmittance of theheat-generating plate 610 according to Example 4 is evaluated as anaverage value of a light transmittance rate in a measurement wavelengthof 380 nm to 780 nm. When the light transmittance is measured by aspectrophotometer (“UV-3100PC” manufactured by SHIMADZU CORPORATION,conforming to JIS K 0115), the light transmission rate is 71%. As aresult, it is confirmed that the heat-generating plate 610 of Example 4has a sufficient light transmittance.

(Example 5) to (Example 9) and (Comparative Example 3) to (ComparativeExample 5)

A heat-generating plates 610 according to Examples 5 to 9 andComparative Examples 3 to 5 are produced by a process similar to that ofthe heat-generating plate 610 of Example 4, and the obtainedheat-generating plate 610 is similar to the heat-generating plate 610according to Example 4 except that the average distance D_(ave) betweenthe median points of the two adjacent opening regions 643 of theconductive pattern 640 and the width W of the connection element 644 arechanged as indicated in Table 2.

Table 2 collectively indicates the average distance D_(ave) between themedian points of the two adjacent opening regions 643 of the conductivepattern 640, the width W of the connection element 644 of the conductivepattern 640, invisibility of the conductive pattern 640 in visualrecognition, the light transmittance of the heat-generating plate 610,and the light transmittance rate of the heat-generating plate 610 inExamples 4 to 9 and Comparative Examples 3 to 5. The invisibility of theconductive pattern 640 in visual recognition is indicated in a column of“invisibility” in Table 2 as A, B, and C. In the column of“invisibility”, A indicates that the conductive pattern 640 is notvisually recognized at a distance of 60 cm from the heat-generatingplate 610, B indicates that the conductive pattern 640 is visuallyrecognized at a distance of 60 cm from the heat-generating plate 610 andis not visually recognized at a distance of 80 cm from theheat-generating plate 610, and C indicates that the conductive pattern640 is visually recognized at a distance of 80 cm from theheat-generating plate 610. The light transmittance of theheat-generating plate 610 is indicated by B and C in the column of“light transmittance” in Table 2. B indicates that the lighttransmittance of the heat-generating plate 610 is equal to or more than70%, and C indicates that the light transmittance of the heat-generatingplate 610 is less than 70%.

From Table 2, it is found that excellent invisibility of the conductivepattern 640 and an excellent light transmittance of the heat-generatingplate 610 can be both achieved in a case where the width W of theconnection element 644 is equal to or more than 1 μm and equal to orless than 7 μm in Examples 4 to 9 in which the average distance D_(ave)is equal to or more than 50 μm and equal to or less than 800 μm incomparison with Comparative Examples 3 to 5 in which the averagedistance D_(ave) is equal to or more than 50 μm and equal to or lessthan 800 μm. Furthermore, it can be found that more excellentinvisibility of the conductive pattern 640 and more excellent lighttransmittance of the heat-generating plate 610 can be both achieved inExamples 4 to 7 in which the average distance D_(ave) is equal to ormore than 50 μm and equal to or less than 150 μm in comparison withExamples 8 and 9.

TABLE 2 COMPAR- COMPAR- COMPAR- ATIVE ATIVE ATIVE EXAM- EXAM- EXAM-EXAM- EXAM- EXAM- EXAM- EXAM- EXAM- PLE 4 PLE 5 PLE 6 PLE 7 PLE 8 PLE 9PLE 3 PLE 4 PLE 5 D_(ave) (μm) 50 50 100 300 600 600 30 1000 1000 W (μm) 7  1  5  5  1  7  7 1 7 INVISIBILITY A A A A B B B C C LIGHT 71 86  81 84  89  86 53 90 88 TRANSMISSION RATE (%) LIGHT B B B B B B C B BTRANSMITTANCE

1. A heat-generating plate comprising: a supporting base material; apair of bus bars to which a voltage is applied; and a heat-generatingconductor supported by the supporting base material and connected to thepair of bus bars, wherein the heat-generating conductor includes aconductive main thin wire that extends between the pair of bus bars andincludes a first large curvature portion having a relatively largecurvature and a first small curvature portion having a relatively smallcurvature, and an inclination of a cross sectional area of the firstlarge curvature portion of a cross sectional area of the conductive mainthin wire is larger than an inclination of a cross sectional area of thefirst small curvature portion.
 2. The heat-generating plate according toclaim 1, wherein the cross sectional area of the conductive main thinwire is divided by a lower bottom having contact with the supportingbase material, an upper bottom arranged at a position facing to thelower bottom, a first inclined portion extending between an end of thelower bottom and an end of the upper bottom, and a second inclinedportion extending between the other end of the lower bottom and theother end of the upper bottom, and an inclination of the cross sectionalarea is expressed by each of an inclination of a straight line passingthrough the end of the lower bottom and the end of the upper bottom andan inclination of a straight line passing through the other end of thelower bottom and the other end of the upper bottom.
 3. Theheat-generating plate according to claim 2, wherein a sum of projectionsizes of the first inclined portion and the second inclined portion onthe cross sectional area of the first small curvature portion on thesupporting base material is larger than a sum of projection sizes of thefirst inclined portion and the second inclined portion on the crosssectional area of the first large curvature portion on the supportingbase material.
 4. The heat-generating plate according to claim 1,wherein projection of the cross sectional area of the first smallcurvature portion on the supporting base material is larger thanprojection of the cross sectional area of the first large curvatureportion on the supporting base material.
 5. The heat-generating plateaccording to claim 2, wherein a gap between the upper bottom and thelower bottom of the cross sectional area of the first small curvatureportion is equal to a gap between the upper bottom and the lower bottomof the cross sectional area of the first large curvature portion.
 6. Theheat-generating plate according to claim 1, wherein the plurality ofconductive main thin wires is provided, and the heat-generatingconductor further includes a conductive sub thin wire for connecting theconductive main thin wires arranged adjacent to each other in at least apart of the plurality of conductive main thin wires.
 7. Theheat-generating plate according to claim 6, wherein the conductive subthin wire includes a second large curvature portion having a relativelylarge curvature and a second small curvature portion having a relativelysmall curvature.
 8. The heat-generating plate according to claim 1,further comprising: a covering member configured to cover theheat-generating conductor, wherein the heat-generating conductor isarranged between the supporting base material and the covering member.